Squeaky door

When a man straps a dildo to his back during a threesome with two women. The women then lay one in front of the man and one behind. The man proceeds to place his penis in the woman in front of him and the dildo in the woman behind him. The then begins to piston in and out fucking both women simultaneously.

Man1: 'God my back is killing me'
Man2: 'What did you do?'
Man1: 'I took 2 girls back to my place last night and gave them a squeaky door. It mustve fucked my back up'