i've had my dog throw up on me before too - only it was worse, he threw up on my hair instead of my shirt
. as much as it sucked, i still couldn't be too mad at him, he couldn't help throwing up, and he was just a little puppy anyway. now that he's older, he's actually "trained himself" to go to the door and ask to be let out when he's feeling sick(guess housetraining carried over to puking too, at least in his case), and the few times he has thrown up in the house since then, he always acts really ashamed about it, like he knows it was bad, but of course i don't get mad at him for something like that(even if it is one of the nastiest things to have to clean up)