Many things that end in the "y" like "minty" or "pony" or "Sweetie."
It's hard to decide, but I think my favourite word is "pony." I like the SEE sign for it, but I flick it back instead of forward. I think that's a cute sign. Don't know if it's the same in ASL because it's a P, but otherwise like horse. Don't get mad, cause I'm gonna learn ASL eventually!
And you can add "pie" to any -y (or -ie) words .. yeah, I'm weird.
When I'm holing a baby or a kitten or something, I talk to it and call it a "cute sweet baby" whatever or something along those lines. I used to do this outloud, but now I'm learning to sign it instead. Have I mentioned I'm weird?
Um, Pinkie Pie is also a favourite of mine, but that's trademarked by Hasbro.
OH YEAH, I just thought of one my sister and I have shared since we were like 3. "Bubble." For us, it means "I'm tired" or "I'm worn out." Nobody else knows this. Well, now everybody who reads this knows, heh, oh well, childish anyway.
Right, I better stop =D