"So Long Mom (a song for World War 3)" seems appropriate right now: https://www.youtube.com/watch?v=yrbv40ENU_o
Probably Lehrer's most famous (and correct) remark outside his songs was when he said that political satire become obsolete when Henry Kissinger was awarded the Nobel Peace Prize. But I think he'd prefer to be remembered for this quote: "If, after hearing my songs, just one human being is inspired to say something nasty to a friend, or perhaps to strike a loved one, it will all have been worth the while."