In TF2, when I'm trying to sneak up on an enemy's sentry nest, my favorite thing to do is disguise myself as a friendly engineer, so that they expect me to help them fix the place up, before breaking out the sappers and stabbers.
This doesn't go over so well when I show up as the engineer guarding the nest.
Assuming I know which engineer it is though, is there a way for me to change which name I use in my disguise, so that I can approach him without danger?