I wish I needed one...
*lonely*

Banana. Never had to use it, which has resulted in some interesting cuts and bruises XD

My go-to is "guacamole", although I usually only adhere to it at my partners request -- otherwise it's just "give it to me until I want it" :P

An alternative:
"Have you ever heard the tragedy of Darth Plagueis the wise?"

Errr I know I have a safe word, it's just I can't remember it!

"Nickelodeon used to have some fire bitches"

Paper for a general no (To rough, no to a question, etc)
Staples for a stop as in well stop, no more sex.

Porkchop sandwiches

I've never had to use safewords... yet. Hopefully one day I will! :3

I have no safe words

"Antidisestablishmentarianism".

I usually use the 'green-yellow-red' system that' standard in the bdsm community.

Sometimes it's watermelon.

"Pen-Pineapple Apple-Pen"
or
"Another settlement needs your help!"
sounds good

"Mi Hoy Minoy!" Hahah! ♥