Well, kind of...
Shipping is a term in fandom to describe expressing interest in romantic or sexual relationships between characters, often known as pairings, or 'ships, from which the term is derived.
Though most often associated with fans who strongly believe or advocate that two particular characters would be successful in a romantic relationship, the exact meaning of the term is loose and open to interpretation, and is sometimes extended to include platonic relationships or those with only a passive interest in relationships, in addition to those fans who fervently create Fanfiction, Fanart around favored couples.
While some fans only casually engage in such speculation, those who frequently engage in shipping are often known as shippers, and when a fan often enjoys two specific characters together they often identify as a pairing-based shipping. Shippers often express their support for their ships by producing fanworks, writing fanfiction entirely about their chosen pairing, although sometimes ships are merely background to the larger story of the fanfic. It is also somewhat more common for even well-meaning or otherwise polite fans to be reflexively defensive of their ships, often taking personal offense when another user discusses it in a negative or even sometimes neutral light.
While the general concept of shipping initially began based on fictional ongoing storylines where romantic or sexual tension was intentionally teased, it is important to note that Canon and authorial intent no longer often dictate people's shipping preference. Characters will often be shipped with little or no regard to their ages, sexualities, canon relationships (even familial), age gaps, or origins, something that has become increasingly controversial. Crack pairings are often denote for those that contain no basis or are implausible by a design.
Nomenclature[]
There's an entire nomenclature dedicated to quick, easy and unique ship naming. The most basic tool of communication here is the slash — if you want to indicate two characters romantically, you might say Name/Name. (As opposed to NameName, which would indicate a platonic relationship, though this usage is rare in the South Park fandom.)
Shipping culture has also imported the Portmanteau Couple Name from various Japanese anime fandom; apart from its infamous usage in the gossip industry (for example, "Brangelina", "Bennifer", "TomKat") you can find people online declaring themselves fans of ships based on this naming format.
Nature of Shipping[]
Shipping is often about the anticipation. Paragraphs and essays and counter-essays weighing megabytes at dozens of pages will be written about who will get together, who should get together, and what the disciplines of political science and feminism and probability theory have to say about the issue (the above is not hyperbole). Some passionate fans will argue endlessly about the romantic nature or future of nearly any given ensemble, but if that point should actually be resolved, the discussions will basically go through a round of ranting and gloating before running unceremoniously run out of steam.
Some have suggested this is because anticipation invites a feeling of reader involvement, while also having a voyeuristic distance, both rooted in the reader's participation as a third party, in contrast to real life romance, which happens directly to the people involved.
Shippers have a reputation of insane devotion to their One True Pairing and of interpreting the tiniest, most ambiguous details as evidence. That much is clear by the prevalence of Shipping Wars in many, many fandoms. In some extreme cases, fans may freely admit to actively rooting for sympathetic characters to suffer or die just to clear the way for a ship, or believe the show's creators intentionally hide evidence as subtle hints towards non-canon ships. A very small handful of shippers sometimes enter fandoms out of love/interest in the shipping aspects of the fandom rather than a true interest in the source material as well.
It is common in all realms of fiction to devote at least some time to tying up the romantic relationships of characters - even South Park itself has devoted episodes due to romantic plotlines - and as a result, almost all fiction focused on human or human-like beings either contains relationships in canon, or in its own fanon. Sometimes the absence of canon romantic relationships only sparks more interest by fans. This is part of why shipping is such a persistent and widespread phenomenon in fandom spaces.
In South Park[]
While shows are occasionally made to deliberately entice shipping, and many serialized dramatic programs craft ongoing storylines from romantic relationships, these elements are not present in South Park, where the comedic focus is usually on male characters, with their relationships only occasionally used as story motivations. The rare romance that does occur is often limited to the children's parents, such as Randy and Sharon. The majority of relationships in the series rarely last longer than a single episode.
As a result of this lack of active focus, some South Park fans criticize shipping culture, though it continued to be the dominant force in the fandom until the late 2010s, particularly when it comes to creative productions such as fanfiction. Character relationships nonetheless became more to the show's forefront beginning in the 19th season, which began featuring multiple ongoing relationships continued in future seasons.
Some fans see the Season 16 (2012) episode "Cartman Finds Love" a deliberate satire against shipping culture, including that of the show's own fandom - however, this has never been confirmed. On the other hand, the Season 19 (2015) episode "Tweek x Craig" was a direct satire of Yaoi shipping culture, and lead to the canonization of a fan-created pairing and using artwork produced and submitted by real fans.
Lead female voice actress April Stewart has referenced the fandom on Twitter, most notably before the episode "Going Native" aired, when she questioned fans about the meaning of a specific pairing.