sweater bullets 

These are nipples protruding through the fabric of a sweater, usually of a braless woman.

It was below freezing, and Melissa's sweater bullets were obvious.

sweater bullets by Elvis Wearing a Bra on His Head January 13, 2007

sweaten bullets 

Nervousness that leads to perspiring.
So scared that you start to sweat.
nervous

When a guy wants to date a young lady, but has to meet her dad for the first time to ask his permission - he might start sweaten bullets while he waits for dad to come up from the basement or start sweaten bullets when dad questions his motives with his daughter!

sweaten bullets by Floridatoy June 10, 2016