Each Saturday during the college football season ESPN hosts College GameDay, an pre-game show with a bunch of football experts and hundreds of screaming college kids in the background.
Today one of those screaming college kids was Sam Crowder, a student who brilliantly decided to hold up a sign with his Venmo username asking his mom to send him beer money.
Cue the Internet, and instead of of getting a few bucks from his mom more than two thousand people sent him money on Venmo, including $50 from Venmo themselves.
I checked OED and there are many definitions for cue. I'm not sure how it is used here.