|1.||it's a commercial|
"I'm only having a laugh." "It's just a joke." "It's only for the benefit of the TV cameras." Said in a condescending tone when you played a trick on someone and want to tell them it's only a joke. Or when you accidentally did something stupid and want to pretend it was a joke. As popularised by Michael Winner on British TV.
Calm down, dear, it's a commercial.