Named after non-toxic Elmer glue, elmer jokes lack the certain toxicity required to make a joke funny. It is not uncommon for an elmer joke to silence an entire room.
a group of friends talking at a restaurant
Friend#1 has finished his dinner except for a few fries
Friend#1: hey do you think I could get this to go?
Friend#2: was that even a joke?
Friend#3: I think it's time to go guys, this guy has started making elmer jokes