Cup with a lid on it, like for children making the transition from bottle to regular, "grown-up" cup. Also can denote a baby bottle, since kids always want to feel grown-up.
Awwww, you dropped your beaky! Bu bu bu, don't cry-- we'll get you some more appa juice.
Mother's babyspeak for a baby bottle.
Awwwww, does baby want his bah-bah? There, there... bu bu bu bu... don't cry.