Skintominute

A skintominute is a unit of time that refers to more than 5 but less than 60 minutes. If person X says they'll be somewhere in 5 minutes, and they're notoriously unreliable, when person Y relays that to someone else they may say that that person X will arrive in 5 skintominutes - meaning they have communicated both what person X said whilst also implying this is a complete underestimation.

Oscar: "Alex said he'll be here in 10 minutes."
James: "10 Skintominutes?"
Oscar: "Yeah, so about 40 minutes