'You can't drink it'

I was having some juice and the girls wanted to share. I told them they could have some later since they'd just finished one bottle. Lavigne then asked me for some sticky tape. As Louisa had just requested for some to do craftwork, I thought the little one was just copying her sister. I passed her some and she went on to stick it across the bottle cap. I asked her what was that for and she replied,' So that you can't drink it.'