Jelly Roll Roasts Trump's Weight and Says He Can't See His Penis

Jelly Roll called President Trump a fat pig on national television ... and somehow the joke only got more personal from there.

The country star was filling in for Jimmy Kimmel Monday night when he brought up a recent Washington Post report about doctors being concerned over Trump's weight.

Jelly noted Trump is now pushing 240 pounds ... before offering some advice from one big guy to another.

He told Trump ... "From one fat pig to another, take it from me that physical fitness is very important. And trust me, you'll be happy to see your penis again."

Jelly was speaking from experience ... joking that his own 300-pound weight loss means he's shed an entire Donald Trump.

He also played a montage of Trump mocking other people's bodies over the years -- including the President repeatedly insisting Chris Christie is "not a fat pig."

Jelly then turned the jokes back on himself, revealing his recent reunion with his own penis left him pleasantly surprised ... because it looked like a "little Labubu doll."