belt down (something or someone)
1. To anchor or fasten something or someone in place. You need to belt down the shed in the back yard before the big storm. Can you please belt down the baby in her highchair?
2. To drink something, often an alcoholic beverage, quickly. He belted down a drink and ordered another before we'd gotten three steps away from the bar.
belt someone or something down
to secure someone or something with a belt or strap. Please belt the child's seat down and put the child in it. Did you belt down the kids?
belt down
Swallow very quickly, as in After the race, he belted down a whole quart of water. This phrase is frequently used for guzzling whiskey or some other liquor. [Slang; mid-1800s]