What are the তালিকা of things আপনি can do with a stop-watch? হাঃ হাঃ হাঃ

In season 1, episode 8, "They keep killing Suzie", at the end of the episode Ianto ব্যক্ত "There's a lot of things আপনি can do with a stop-watch.", probably sexual things because of the looks he and Jack shared.
I was just wondering exactly WHAT can আপনি do with a stop-watch. Even my sick mind couldn't figure THAT out.
Do আপনি have any idea? XD