Tension Ball

Noun: A bold claim on how or why something is or isn't, when you are blatantly wrong. False confidence in a false fact.

Person 1: Hey what are those balls on the telephone lines for?
Person 2: They keep tension on the lines. For sure.
Person 1: *googles it* Thats just not even a little true
Person 2: Wait really? Weird.
Person 1: That was a pretty bad tension ball...