So the saying "be yourself" isn't literal? This is why I don't understand it.
We should change it to 'behave how you want'. That way you can say that you're doing what you want, and aren't pretending to behave like someone different.
If pretending is funny to you and you want to do it, then you aren't actually trying to be someone else are you? Seems pretty literal to me dude. By playing a few pretend games as a joke, you're doing just fine being yourself, since your sense of humor is part of your personality.
BAM!
I don't think the context you use is a literal interpretation. Being yourself, to me sounds absurd, because how are you meant to be someone else.
You are being yourself by playing to your sense of humor. You're not being someone else, you are temporarily pretending for a laugh.
By abstaining from making these jokes as you normally would around people you don't know, you are deceiving them since your sense of humor is a part of you. By concealing parts of yourself, you are not being yourself. Hence you are basically lying.
Checkmate.
"Is she gone yet?"