1. sth that is more expensive than it should be, very expensive
those shoes are a rip-off, that handbag/meal is/was a rip-off
A 'rip-off' is a noun describing an object that is overpriced or unfairly expensive. "Paying $5.50 for a simple cup of coffee is a rip-off. This expression is quite informal and more likely to be used in social situations. You can also use 'rip off' as a phrasal verb, meaning to overcharge or make someone pay a lot for something.
2. an imitation (usu. a bad one)
a rip-off of a famous brand, rip-off handbag/sunglasses/watch
A rip-off can refer to a poor imitation or something such as a fake designer handbag for example. "The new line of clothes by the retail store is a rip-off of looks made popular on the catwalk." This expression is quite informal and more likely to be used in social situations.