Have had one too many
Definition 1 of 2
Pro Tip 1/3Colloquial Usage
Used mainly in informal settings among friends or at social events. 
Dave won't remember tonight; he's had one too many.
Pro Tip 2/3Subtle Concern
Can imply worry for someone's well-being after drinking a lot. 
You should get some water—you've clearly had one too many.
Pro Tip 3/3Euphemism
A polite way of indicating someone is drunk without saying it directly. 
Let's grab a cab. Helen has had one too many.