This is a term introduced by UFC Featherweight Champion Conor McGregor, who is a large Pay-Per-View draw and, in turn, a large pay day for whomever fights him (win or lose).
"I can make you rich. I change your bum life. You fight me, it's a celebration. When you sign to fight me, it's a celebration. You ring back home, you ring your wife. 'Baby, we've done it. We're rich, baby. Conor McGregor made us rich. Break out the red panties.'" - Connor McGregor
"I just got a raise! Now we can finally afford that Honeymoon in Paris that you've always wanted. It's a red panty night, baby."
Craig : So how was you and the wife's date night last night?
Chad : It was rather boring until we got home & found the babysitter Keirsten on the couch caught up in a panty pleasure, I developed a instant chubbie and jized in my pant's!
Craig : Nice!
"Panty" (pronounced pan-tee) refers to a woman's underwear. A Panty Charmer is a person who flirts with, and gets along well with women, regardless of whether or not their aim is to get into their panties.
This term is similar to lady-killer, but it is less insidious.
Mike: "Nice panties Jill"
Jill: "You're clearly *not* a panty charmer, Mike"
Jill: *discretely reports Mike to HR*