POTUS was gifted the headgear just minutes after he praised the team for winning its second straight championship ... and when Patrick Mahomes, Travis Kelce and the rest of the guys urged him to throw it on his dome -- he did just that!

The 81-year-old -- with help from head coach Andy Reid -- unbuckled the chinstraps ... and squeezed the protective gear over his noggin. He then put his hands up and motioned for Mahomes to throw him a pass.

He then walked around the stage with it for several more moments -- even at one point going back to the dais to say a couple words!

All of the Chiefs in attendance loved it -- they giggled the entire time -- but Biden eventually took it off and concluded the ceremony.

It was hardly the only funny moment at the event ... as at one point during the speech, Biden invited Kelce up to the microphone to say a few words.

The KC star jokingly addressed the crowd as "my fellow Americans" -- before he stated he wasn't going to overstay his welcome.

"I'm not going to lie, President Biden, they told me if I came up here I'd get Tased," he said, "so I'm going to go back to my spot, all right?"

As for the All-Pro's famous girlfriend, Taylor Swift, she didn't make an appearance -- and, surprisingly, Biden didn't make reference to her.