This happened to a friend of mine in high school.. it was pretty gross .. actually somewhat similar to bucutie's story.
It was after a football game party.. we went to Whataburger b/c it was the only place open so late. My friend ordered one of their strawberry shakes... and she couldn't figure out why she wasn't getting any more of the strawberry stuff no matter no much she tried sucking on the straw. She opened up the lid to find a HUGE roach at the bottom of her cup