@alpine_thistle is that the vertical bus

@alpine_thistle

When we were kids we used to play a game where you would draw a little army on your side of the paper and the other person would draw one on their side. Then you took turns putting a pencil upright, point donw, on one of your 'troops', putting one finger on the eraser, then pushing down to pop the tip out toward the other side. If the line crossed an enemy figure, it was dead.

This drawing reminds me of that game.