Question: When I was growing up in the late '70s and early '80s. I remember there was a show about Sinbad the Sailor in which he was a skinny regular guy, but once he squeezed his belt, he became Sinbad the Sailor. I'm not sure now if it was a movie or a show. If you have any information, please help. I think I'm the only person in the world who remembers this crazy Sinbad.
Answer: Only if you don't count me, which (sniff) is often the case.
It sounds like you were probably watching a syndicated package of the animated Sinbad Jr., the Sailor, aka The Adventures of Sinbad, Jr., which was produced by Sam Singer beginning in 1960 and finally released along with newer episodes produced by Hanna-Barbera in 1965. In the show, the titular Jr. was the son of the original Sinbad and, as you say, was a stickpin of a boy who gained superpowers by activating his belt. His first mate was a wacky talking parrot named Salty because, as you know, Newton's fourth law states that all Saturday-morning cartoons must include a funny animal to provide comic relief. Seriously check any physics text.
Notes for you voice fans: Tim Matheson (Animal House, The West Wing, the original voice of Jonny Quest) provided Jr.'s voice (credited as Tim Matthieson), while Mel Blanc voiced Salty.