For me, "I ship it" means usually "I enjoy imagining them together" and "I enjoy fanworks about their relationship." (Some relationships I have trouble writing, but love reading them/want to read them.)

I actually...don't know where the boundaries between "romantic relationship" and "friendship" are, so when I write shippy fic I always worry about not being romantic enough. I love the idea of romantic friendships, though, but it's hard for me to write fic with all the cuddly/handholdy/sleeping-together-without-sleeping-together stuff I'd like, because ID.