knee-high to a grasshopper
Quite young, as in I haven't seen him since I was knee-high to a grasshopper. This hyperbolic expression, dating from about 1850 and alluding to someone's youth, replaced the earlier knee-high to a mosquito or bumblebee or splinter.
Words nearby knee-high to a grasshopper
knee spavin,
knee-chest position,
knee-deep,
knee-elbow position,
knee-high,
knee-high to a grasshopper,
knee-jerk,
knee-jerk reflex,
knee-length,
knee-slapper,
knee-socks