New Secret Service Agent

The president is leaving the White House and walking towards his limo, when a possible assassin steps forward and aims a gun.
A secret service agent, very new on the job, sees the threat and yells, “Mickey Mouse!” This startles the would-be assassin and he is captured.
Later, the secret service agent’s supervisor takes him aside and asks “What in the hell made you shout Mickey Mouse??”
Blushing, the secret service agent replies, “I was very nervous. I meant to shout “Donald, duck!”