Nothing quite so much fun as going to the check-out at a hardware store w/ rope and assorted recreational hardware to have the check-out girl ask:

"Ummm.... are you going to tie someone up with this?"

and to be able to respond with a "Yes" while smiling wickedly.

(my only regret was not flirting with her more actively to see if she was into BDSM, but I was actually buying things for use on someone I was seeing at the time so I really couldn't)