say that ur gonna go smoke and ask her if she wants to come. and yeah she fuckin smokes why the hell else woudl she have a pot leaf on her myspace
Pull out bowl/bong/joint/blunt and say "I'm gonna go smoke, you don't mind do you?" and most likely she'll toke up with you.
"Accidentally" let a joint fall out of your pocket in front of her and see what she says. Although that would be incredibly dorky and awkward. She smokes.
Pay someone on the street to be your friend for an hour, then set up a lunch w/ you, the stranger, and the girl. Then have the guy bring up pot and see how she responds. Like with others in this post, I agree you should just ask. I can totally relate to your problem though... it's hard to make that jump with someone you really like.
Just ask her, and if she doesnt make fun of her for being a stoner wana be, she'll think u cool man! Then go smoke wif her!