Note, I'm not suggesting you do any of these, but gosh they'd be momentary fun until you decide to follow Ed,sr.'s good advice.
Sign her up for the Adam & Eve or other kinky catalog, at her work address. Also Victoria's secret, etc.
Syrup in the gas tank. Yum.
Sleep with her best friend, sister, and cousin. All at once. Make sure to videotape, so you can share with your brothers here and her later.
Have one of your friends start hitting on her so as he can get some good porno shots for you.
Does she have a cat? there's a great target for paintball guns. Helps you with the leading shots on moving targets I hear.
When she's about to leave after getting her hot beef injection, somehow get gum in her hair. Bad hair week, coming up!
Also, try and slip the used condom into her purse while she's not looking.
If you can....shave one of her eyebrows. Pencil it back in if you can so she doesn't notice immediately.
Like I said....I wouldn't do any, or recommend that you do any of these. But it's fun to speculate.