After reading the Harry Potter series, every mention of it will cause a devastatingly long discussion about characters and events in the novels.
Generally, you are Potter prone if you do such things.
1: Hey, that guy kinda looks like Hagrid!
2: Hagrid! I love that guy. Did you know he was accused of opening the Chamber of Secrets? Did you know he had a pet spider named Aragog? Hagrid likes dragons too. He was a member of the Order of the Phoenix. Did you know he brings Harry to the Burrow when Harry turns 17? Did you know...