I had this thought as well, but figured I'd make sure no one else already posted it. Kudos :). I was thinking something like this:

> Do NOT give ANY hints; only accept an EXACT answer; I will NEVER say I "forgot" this answer. 2DXSDGREDV@#!

Maybe add an "I test you occasionally." :D

If there's a length limit, trim and remove parts of that as you see fit. For example:

> NO hints! EXACT answer! NO exceptions! 2DXSDGREDV@#!

I'm going to do this at a few places, then call to test them :D.