A Sub-Trope of Don't Explain the Joke, wherein the teller of a failed joke follows up with some variation of "That was a joke." Differs from I Was Just Joking in that an integral part of I Was Just Joking is that the listener takes it completely seriously. Here however, it's simply not funny. Up for Grabs.
Hello, Unknown Troper. You'll need to get known to lend a hand here.