A fandom loves Shipping. The media they're a fan of is comprised pretty heavily of children. As a result, the most popular couple in the show may end up being composed of two kids. This results in the occasionally squicky practice of Shipping two characters who are barely old enough to be in a relationship (but in fairness this isn't as squicky as pairing them off with adults).
A Toy Ship does not automatically qualify as squick since usually people only support innocent childhood crushes or affection between the two; most writers and fanfic authors will never go beyond the point of hugging, soft kissing and declarations of love, or they will wait for the characters to be depicted as adults in canon before anything.
For In-Universe examples of kid couples, see Puppy Love. Not to be confused with Cargo Ship, which is about shipping people with things like toys.
