Although this bullshit button is quite similar to Staple's Easy Button, and both are actually available for purchase, the bullshit button actually does something useful. See, whenever your buddies make some outlandish claim, just slam on this button and it'll pop out one of five "clever" sayings.
• "(Beep) That was bullshit"
• "(Siren) Bullshit detected, take precautions"
• "Bullshit level defcon 5"
• "Oh, come on now, that ain't even bullshit, that's horseshit"
• "Warning, warning, bullshit alert"
Plus, it's useful whenever you're actually playing the card game.