When you use a can of beer like a fleshlight and then ejaculate into it, then mix it up and offer it to your girlfriend.
GF: "Hey Babe can you get me a drink?"
You: "Yeah sure, you want a Cherry Cream Ale?"
GF: "Sure? I don't remember us getting them but I'll try one."
You: "Okay, give me 5 minutes. And maybe turn up the music."