Lyndon B Johnson

but I read an anecdote supposedly by a member of Johnson's secret service detail that once LBJ pissed on the back of a secret service agant's leg while waiting to do a speech and told the agent "Hell, son, I'm President. It's my perogative". I can't see it being true, but stranger things have happened.

He was a hard drinking, foul mouthed Texan. They had a bell rigged up in the Oval Office, so that if Lady bird made an unexpected appearance, the SS would ring it so LBJ wouldn't get caught in one of his dalliances.
It may have been the guy that got his leg pissed on, but one day Lady Bird comes into the Oval Office and catches LBJ on Obamas desk screwing some chickypoo and no one had rung the bell...LOL