watch one's dust

watch one's dust or watch one's smoke  {v. phr.},  {slang}
To notice your quick action; watch you do something quickly.
Offer Bill a dollar to shovel your sidewalk, and watch his smoke!
"We'll have your yard cleaned in a jiffy," the Boy Scouts told Mr. Truitt. "Watch our smoke!"
"I can go to the store and be back in five minutes," bragged Tom. "Just watch my dust."
Categories: slang verb