A pegging train is when two women are fucking two men with strap-ons, and each man is fucking the woman in front of him, all connected as if they are in a conga line.
Two couples made a pegging train when they joined together: I pegged him, he fucked her, she pegged her guy.
Started with Pirates sticking their peg legs in each others ass... since there were no women around while at sea for long periods. Quickly grew in popularity when they switched from peg legs to dildos.
Sébastien drops pen and picks up seductively while peaking over his shoulder...
Susan notices and can't keep composure....