During a SXSW show Thursday night, LADY GAGA had a woman VOMIT on her repeatedly while she performed.  The woman is a performance artist and "Vomit Painter" named Millie Brown.  She was drinking colored soy milk, then shoving two fingers down her throat to bring it back up all over Gaga.

WARNING!!! There are UNCENSORED F-BOMBS. Also, it's kind of gross ... especially if you have a weak stomach for this sort of thing.

CLICK HERE TO WATCH THE VIDEO

And here's Millie's website.