The area behind a vehicle moving through something where there is not so much air resistance (if moving through air. This can be used to gain speed before overtaking someone in a race.
Also if in space when your spaceship is in the slipstream of another it can't be detected by the other ship's sensors (but this is only if you are in an episode of star trek).
Ooh ooh he's going to overtake him, he's gaining speed in the slipstream.
YES! he's done it and the crowd goes wild.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.
We have a Zoom meeting in a few minutes and I’ll probably go pajama casual.