Many dogs regard vomiting as a means of artistic self-expression. My late dog Tucker (seen here with Tessa when she was a pup, in 1996) was of this mind. As a true artist, he was fussy about where he barfed, preferring to place his finest oeuvres in a suitable spot, usually the middle of my living room rug.
Dogs with a sense of humor will sometimes vomit silently next to your bed, then whine until you get up to let them out. Inevitably you step in it with your bare feet, which they think is a hysterically funny joke. Tucker used to do this, too. It bothered me at the time, but I'd gladly step in it every morning to have him back again.