Definition
This idiom describes a person who has a low tolerance for alcohol and quickly becomes intoxicated or experiences adverse effects from drinking even small amounts.
He started slurring his words after only two beers; it seems he really can't hold his drink.
I know you don't drink often, but if you decide to drink, please remember you can't hold your drink.
She felt dizzy after only a small amount of wine; she really can't hold her drink.