grandma knees

Resulting from consuming large amounts of alcohol or smoking too much weed, grandma knees occur when a person begins to lose their balance and begin to cripple at the knees. This phenomenon is similar to knee struggles that elderly women have.

guy #1: How the fuck did you walk home last night you shotgunned two four lokos before you left the party?
guy #2: Trying to walk home was hell, I had a terrible case of grandma knees.