Don’t swindle your readers out of a good reading experience by getting these two words wrong.

Rip-off is a noun meaning that a deal is unfair or a scam: Aunt Janie knew the purse’s cheap quality made it a rip-off given the high cost.

Rip off (without a hyphen) is a verb in which you steal from someone: The scammer used a bogus ad on Craigslist to rip off the unsuspecting buyer by taking his money but delivering no services.

The easy way to remember the difference is that the noun takes a hyphen. The verb doesn’t have one (because it was stolen, no doubt!).