To become less serious; be easy; relax •Often a more or less gentle admonition: Schofield lightens up and improves at bat/ Aw, come on, everybody, lighten up a little. It wasn't that bad. The decade, I mean/ You have to lighten up, Chief. The men are giving it everything they have (late 1960s+)
Peil: I think Grams would have said to Jackie, “You have to lighten up.”
Some partisans undoubtedly thought Eastwood was funny and that the MSM should lighten up.
IF YOU ARE OFFENDED, SKIP OVER, OR lighten up AND GET A LIFE.