lose (one's) cherry
1. vulgar slang To have sexual intercourse for the first time. There is nothing wrong with waiting until you're absolutely ready before you lose your cherry. Too many people try to pressure you into it from too young an age.
2. vulgar slang To do something for the first time, often that which is particularly daunting, difficult, dangerous, illicit, etc. Somebody pass Marcus the joint, he still needs to lose his cherry tonight! For her birthday, I bought my friend Samantha a voucher so she could lose her cherry sky diving.