Alan: Tell me about it, here he comes.
Daryl: Hey guys, how you doing chickens?
Alan: Definetly a chummer
Daryl: Eh? Chummer?
A type of person who is a proper loner, sad twat, armed with pointless questions to gain attention and/or to gain friendship, only to piss off and weird out the person(s) they are engaing in conversation with.
Basically a step up from a sex offender and a step down from a train spotter, anorak the lot
Office worker Brian spots this and says to co-worker Antony "look at this chummer"
Quit being a chummer, we were supposed to go grab some beers and check out the show.