to stagger along, to fall
蹱 centers on unsteady, stumbling movement: staggering along or falling due to loss of balance.
蹱 combines 足 (foot) with 童, which likely contributes the sound. The exact historical development is uncertain, but the foot radical points to movement, fitting the meanings of staggering or falling.
The left side is 足 (foot), and the right side 童 suggests a child. Picture a child's unsteady feet staggering and falling as they learn to walk.
For ショウ, imagine a staggering person being shown the way: show -> ショウ, as someone helps them up after a fall.