The largest contributor to Donald Trump's charity is a man he did some very public business with inside a pro wrestling ring nearly a decade ago.

World Wrestling Entertainment owners Vince and Linda McMahon donated $5 million to the Donald J. Trump Foundation between 2009 and 2014, according to a list of contributions released by the Trump campaign. Incidentally, Trump didn't donate any money to the foundation during that time, the Washington Post reported.

The McMahons' contributions came after Trump and WWE chairman Vince McMahon had a scripted feud on WWE television in 2007 labeled "The Battle of the Billionaires."

The feud culminated at Wrestlemania 23, when Trump and McMahon each chose a wrestler to face off in a match. The losing "billionaire" would have his head shaved during Wrestlemania.

Trump's wrestler won, but not before the GOP frontrunner body-slammed McMahon outside the ring. McMahon subsequently had his head shaved completely bald.