A term used by bronies when they boast that they can do something fast. It originated from ep. 1 of My Little Pony: Friendship is Magic when Rainbow Dash stated that she could "Clear all the clouds from the sky in 10 seconds flat"
Hey, I just beat your best time in Mario Cart!" "Meh, I could do it in 10 seconds flat.
MOTHER FUCKING RAINBOW DASHによって 2011年06月12日(日)
A common term of unknown origin, in which a person claims to be able to complete a task in 10.00 seconds. Existed long before the existance of My Little Pony: Friendship is magic
You see that tree over there? I can run there and back in 10 seconds flat.