It wasn't really toilet paper, it was a seat cover, but it was enough for a smart guy to make the connection.
9 seconds sound clip from the Dead Men Don't Wear Plaid movie soundboard.
You can hear this line at 00:28:46 in the Blu-ray version of the movie.
Quote context
[...]
- Inside were two long lists of Carlotta's friends and enemies.
- The first name that jumped out was FX Huberman, number 46 Bay Court Drive, Grunion Point.
- I decided to take a little train ride and visit Mr Huberman.
- There was no way he could follow me unless I had toilet paper stuck on my shoe... Damn!
- Oh! I beg your pardon. Was that your leg?
- I had no idea we were going into a tunnel.
- I thought the compartment was empty.
- I'm so sorry. I hope I didn't hurt you.
[...]