found this on the net:

20 Ways to Annoy Public Bathroom Stallmate

1. Stick your open palm under the stall pader and ask your neighbor, “May I borrow a highlighter?”

2. Say, “Uh oh, I knew I shouldn’t have put my lips on that.”

3. Cheer and clap loudly every time somebody breaks the silence with a bodily function noise.

4. Say, "Damn, this water's cold!"

5. Drop a marble and say, "Oh sh*t, my glass eye!!"

6. Say, "Hmm, I've never seen that color before,. . ."

7. Grunt and strain real loud for 30 segundos and then drop a cantelope into the toilet bowl from a height of 6 feet. Sigh relaxingly.

8. Say, “Now, how did that get there?”

9. Say, "Humus. Reminds me of humus."

10. Fill up a large flask with Mountain Dew. Squirt it erratically under the stall walls of your neighbors while yelling, “Whoa! Easy boy!”

11. Say, "Interesting,. . . madami floaters than sinkers."

12. Using a small squeeze tube, spread mani mantikilya on a wad of toilet paper and drop the wad under the stall pader of your neighbor. Then say, “Whoops, could you kick that back over here please?”

13. Say, "C'mon Mr. Happy!! Don't fall asleep on me!!"

14. Fill a balloon with creamed corn. Rush into the stall with your hand over your mouth and let out a lengthy vomit impression while you squeeze theballoon and splatter cream mais all about. Apologize profusely and blame it on the fettucine alfredo you had for breakfast.

15. Say, "Boy, that sure looks like a maggot!!"

16. Say, “Damn, I knew that drain hole was a little too small. Now what am I gonna do?”

17. Play a well known drum cadence over and over again on your butt cheeks.

18. Before you unroll toilet paper, conspicuously lay down your, “Cross-Dressers Anonymous” newsletter on the floor visible to the adjacent stall.

19. Lower a small mirror underneath the stall wall, adjust it so you can see your neighbor and say, “Peek-a-boo!”

20. Drop a D-cup bra on the floor under the stall pader and sing “Born Free”