Haha. The alcohol part is an assumption made by allkpop and viewers.
So, I find it hardly fair to believe.
To be honest and all, skipping class isn't that big of a deal and I am not saying this because I am a fan of Nicole and all. I bet tons of Korean college students do it all the time. Nicole can't be the perfect student, she's only human.
*TOTAL SIDE NOTE:
This sort of reminds me of the time Seo in Young did this show, she didn't even show up on the first day. Haha.