Paying £10 for a bottle of water at the airport felt like a total rip-off.

rip-off 是一个复合名词，由 rip（撕开、扯走）和 off 组合而成，字面带有"把东西硬扯走"的意味，引申为"敲竹杠、宰客"，指价格明显高得离谱、让人觉得被坑的买卖。