The FoxTrot page-a-day calendar has Jason/Quincy handing a box of glowsticks to Peter and saying:
Use these glowsticks if you see British troops approaching.
One if by land, two if by sea. [next frame] Three if by air. Four if by land and sea. Five if by air and sea. Six if by land and air. Seven if by land, sea and air. Eight if by underground tunnel. Nine if by teleporter. Ten if by other.
For some reason, I think it would have been more geeky if he had continued like this:
Three if by land and sea. Four if by air. Five if by land and air. Six if by air and sea. Seven if by land, sea and air.
That would have been equivalent to bit 0 = land, bit 1 = sea, bit 2 = air.