I was watching a bad 1933 Jimmy Cagney movie recently called Picture Snatcher. Actually, it had a decent idea at its core: Cagney is an ex-con turned tabloid photog/reporter, the Irish Weegee. Unfortunately, the script was terrible but it did contain a piece of '30's slang that made my ears perk up. Jeez, now I sound ike Oscar the cat.
Anyway, the Cagney character was gassing with his girlfriend's copper father, complaining about people who talked a lot and had nothing to say:
Some people waste a lot of time bumping gums.
It also sounds like an attack on gum chewing, which is something I cannot abide, but that's for another day. I'll let Elvis Costello have the last word: