When your vehicle's turn signal indicator syncs with the beat of the music that's playing from your car's stereo, either by matching or alternating with the beat of the music. See Wiper Beat.
Tick, tsch, tick, tsch, woomp, tick, woomp tick...
Hey check out this crazy blinker sync!
When you are stopped waiting for a turn, most often a red light, and your blinker synchronizes with the person's in front of you blinking at the same exact time and rhythm.
GUYONE: "I was just waiting at that red light waiting to go left and my blinker was blinking at the same exact time as the guy in front of me!"
GUY TWO: "Nice blinker synchronization!"
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.