1. An approximated date when all multicellular life forms will die out.

2. An exaggerated statement for how long something may take.
“Hurry up! Is my food ready, a billion years later?”

A billion years later, we’re all gonna die! Better start making the most of it...”

“Apparently, according to scientific belief, sentient life expires from this solar system supermarket at least a billion years later, and is also when I expect to get my ice cream cone by; assuming my friends can’t be slower than they are, already!”
by Smith dux Wurd November 20, 2017
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