A couple years ago I did this, not a success, but a number and a good story.
I was at a resaurant with friends and in walks a girl with her mom. They sit down in another section of the restaurant from us. I tell my friends I'm gonna try to get the girls number while she's with her mom. They say they'll buy me a beer if I can do it.
I let them two of them get settled for about 10 min. and I head over to their booth, grab a chair from a nearby table and pull up to their booth.
I say hello to the daughter, introduce myself and she tells me her name. I ask the daughter what her pretty sisters name is. Mom laughs, and alerts me that she is really the girls mom. I tell mom that she must get that alot, we laugh and I small talk with the daughter.
After some awkward small talk (I was still new at this at the time) I ask the daughter for her number, she says sure. I look for my cell and can't find it. The daughter pulls out a napkin and proceeds to paint her number on the napkin with a knife and ketchup.
I'm thinking I'm in, because after all I'm an idiot and I have no idea how to judge interest at this point in time. I figure she's going through all this trouble to give me her number, I'm so fvckin in!
Halfway through her number painting with the ketchup I find my phone and give it to her. She playfully complains that I made her go through all that trouble, and I retourt with something stupid.
I wish the two of them good evening and head back to get my free beer from my friends, which is a sweet deal since I was under 21 at the time and our waitress wouldn't serve me.
The story ends with a fake number. Sorry.
Lesson: It can be done, and it can be fun.
Mr. Mystery