This really isn't all that different from his old friend and former presidential candidate John McCain (dodged a bullet there), singing 'Bomb Iran' to the tune of the Beach Boys' 'Barbara Ann.'
"Bomb Iran" (or "Bomb, Bomb, Bomb, Bomb, Bomb Iran") is the name of several parodies of the Regents' 1961 song "Barbara Ann", originally written by Fred Fassert and popularized in a "party" cover version by the Beach Boys in 1965. The most popular of the parodies was recorded by Vince Vance & the Valiants in 1980. "Bomb Iran" gained a resurgence in notoriety in 2007 during John McCain's 2008 presidential campaign.
I think Graham is just a sleazy politician and knows it will give him more clout. Republicans who have taken a stand against Trump have mostly ended their careers; it's been a surprising amount of courage from some individuals I didn't think were capable.
Lindsey Graham doesn't have brain worms, he is the brain worm.