"What makes you tick" is an idiomatic expression that means "the things that cause someone to behave a certain way: the feelings, opinions, concerns, etc., that are parts of someones personality". It refers to the basic drive or motivation of a person. It is often used to ask someone what motivates them, what interests them, or what they like. The expression can also be used to describe the thoughts, feelings, opinions, etc. that give someone their character or make them behave in a particular way. Other similar phrases that convey a similar meaning include "whatever makes you tick" and "what motivates you".