Hmmm I haven't really done anything to desperately funny...
But one time I got a hold of one of my friends cell phones when he wasn't around, and swapped my number on his phone for a girl he had a crush on since way back in 3rd or 4th grade, and just left it alone... I never told him about it, it had the same name and he thought it was still me.
So a couple months pass with him texting her thinking it was me, both oblivious to the swap. So, he plans on having a big guys party where we all would go out and hang out at the movies and then go have a sleep over at his house... kinda of like a party for the beginning of summer, and he ends up inviting her to the sleep over at his house, and she actually shows up to the movies
I'm assuming it was out of sheer pity for the poor boy that she came, but I can still remember the look on his face when she walked in the door, priceless... it kind of looked like this smiley --
Well there is more to the story that happened that night, but alas I should say no more
I smile every time I think about it