I can only explain that has having a "God Given Gift". Jack Benny was like that. Stan Laurel. And there are some today as well...
They can simply appear on camera and you'll giggle. And I do not think it's just 'me'.
Not too long ago I wrote about watching "It's A Mad, Mad, Mad, Mad, World" with my grandsons... and they loved it. The favorite scene for my grandson, who is now 13 but at his first viewing of the movie was 11, in the entire movie was during Jack Benny's cameo when he say's one word - - - "Well".