Friendly pieces flanking the king like shoulder boards
A king is checked while two of its own pieces sit on the adjacent squares to its left and right, blocking lateral escape. The flanking pieces look like military epaulettes (shoulder boards). The checking piece often delivers along the file or a diagonal, and the king cannot step sideways because its own pieces wall it in.
Bishop takes the d4 pawn. Mate. The bishop checks the king on f2 along the diagonal. White's own pieces on e2 and g2 lock out the lateral escapes. The king cannot move sideways, the epaulettes hold it in place.
Go on then, take it.
3 more clean runs (at any point) to reach Recall.
Black to move. White king has just stepped to f2 to grab a knight. The d4 pawn looks loose, and Black has a bishop on f6 aimed straight at it.
3 more clean runs (at any point) to reach Recall.