A "ticker" is any person who participates in a hobby that contains a large number feats to be accomplished whereby their personal understanding of success or victory in this field is correlated to how close to 100% of the accomplishments they can "tick" off their list. This applies to hikers looking to summit the highest peak in all 50 states, bird watchers, visiting the countries of the world, trying all of the restaurants in a large city and bedding every last male and/or female on the planet.
This term is often used in a pejorative sense as oftentimes the desire to "tick" things off one's list interferes with one's actual enjoyment or even awareness of the act. Ticking is also almost always associated with some degree of nerdery.
Bill tells me that he "reviewed" 120 beers at the beer festival. I think he's full of shit saying he remembers them all and that he's probably just in it for the numbers so that he can brag to his stupid friends. He's just another ticker.