Thought of some things I do when I'm around other people and don't want to be.

1. Practice thinking in foreign languages.
2. Recite poetry to myself (in my head)
3. Conjugate verbs in a foreign language.
4. Daydream
5. Read Failbook
6. Go grocery shopping.
7. Read a cookbook/plan a menu
8. Contact someone I haven't talked to in ages

That's a sort of stressful homework assignment! 30 should be enough