[Lucas89]

Originally Posted by Yuusuke

u can say

nomitai ja nai.

you actually just drop the い at the end and add on くない
making
飲みたくない - Don't want to drink

nomitai ja nai is wrong

Edit:
For ～たい it just changes like an い adjective

so for example:

飲みたい - want to drink
飲みたくない - dont want to drink
飲みたかった - wanted to drink
飲みたくなかった - didnt want to drink