slack or not???

Three girls are sitting on stools at a bar. The 3 of them are arguing on who is the slackest. The first one says: "My boyfriend can put his whole fist in my pussy¹!!!" The second one says: "Oh ya? Well my boyfriend can put his whole head in my pussy!" The two of them then look at the third one, waiting for her to reply. She then looks at them and says: "Oops! There goes the stool!!!"