Definitely on the computer or behind somewhere where it's hard to reach to clean it up. It will be sticky and attract bugs yuck. Plus it can ruin the computer and that's no fun.
on my binder of finished drawings ive done and spent hours trying to perfect and have kept safe with sheet protectors that have that stupid opening on top in which coffee can seep through and ruin everything!
The coffee stain would never come out.
that lucky!