Under your desk. Maybe you just happened to check your phone while you were drafting a work email, and maybe you got a text from your hookup along the lines of: "I don't want to be presumptuous, but it feels like you want something more serious than I do, and I'm not in a place right now where I can commit to anything but would be down to keep hanging as friends, though." Go under your desk and rock back and forth. Intentionally bump your head when you finally come back up so you have an alibi if someone asks why you're crying. You were down there to plug in your charger, and bam! Also, you did want something more serious than he did, but that is not the point, and he should know that.