I used to have "performance anxiety" when it came to pooping in public bathrooms as well! However, a semester of commuting to college for sometimes 9 hour days forced me to do it from time to time. Here's what I do:
1. Get a wad of toilet paper and wipe toilet seat off.
2. Cover the toilet seat with several layers of paper.
3. Get another good size wad of toilet paper and put it directly in toilet.
4. Poop.
#3 helps because it greatly reduces the chances of the nasty public toilet water spla
shing back up on you, AND it reduces noise (in the case that you're embarrassed about the "plopping," so to speak).
