I was wondering, why did Andy drink those shots in the "Cross Hands" Pub since he's supposed to be teetotal ?

I have my theories but feel free to post your own.

1/
He feels pressured by the fact that the others want him to drive.

2/
He's craving for alcohol ;) (come on 16 years!?)

3/
He prefers Steven's plan 

4/
He secretly likes a waitress in "The Good Companion"

5/
Just because the plot needs him to...