The "Colonel Sanders" is when your girlfriend or wife gives you oral sex. You cum above her upper lip and make a mustache. Then you put a little on her chin, for the goatee.
There are a couple variations to this:
A "Colonel Sanders with a Pearl Tooth" is the above action but when your partner smiles, you squeeze a little cum on her front tooth.
A "Colonel Sanders with a Monacle" is the above action and you put the last bit of cum in her eye.
He wanted to surprise his girlfriend so he gave her the Colonel Sanders