How to deal with getting caught with alcohol in your room?

I was with a friend last night and we drank for a while and i filled a poland springs bottle with only a little bit of vodka for later and then today my mom was suspiciaous that i was smoking so there is a chance she went looking through my room. nd i called her to ask if she could take me somewhere and she said yes but mentioned that there has to be parents home and that she isnt puting up with drinking which leads me to believe maybe she went looking in my room for the vodka. she is picking me up in about a hour and i think she is going to confront me about it in my room what do i say and how do i react to make her less mad?