Just found out the definition for дрочка ... hehe!
Two related rhyming phrases for the interest/entertainment of us foreign learners -- the first is traditional; the second is from a poem by Иосиф Бродский.

Каждый дрочит, как он хочет. (lit, "Each one wanks as he wants" -- in other words, "Everyone has different tastes")

and

Между прочим, все мы дрочим. (lit., "By the way, we all wank")

To repeat what alexsms said, the word is quite rude -- so it's good to understand, but as a foreign student of Russian you should generally avoid using it!

P.S. English usage note for Russians: to my American ears, "wank" sounds rather mild and funny, but I believe it's ruder and more graphically sexual in UK English. It's the opposite for the US English "jack off" -- quite rude in the States, but milder in the UK, as far as I know. (Just one of the many differences in English depending on the side of the pond you're on...)