Algebra Pickup Line

Okay, listen up, buttercup. This joke is all about being smooth with the ladies. The joke teller is saying that they're good at algebra (you know, math with letters and numbers) and can replace "X" (a letter used in algebra) without even asking "Y" (another letter). But the letters X and Y also sound like "ex" and "why." The joke teller is being clever and is saying they can replace their "ex" (X) without even asking "why" (Y). See, algebra and love mix!