On random days I will speak to everybody in Iambic pentameters with heroic couplets. On other days I will blurt out rhymes to the word the other guy uses to end his sentences.
Building invisible structures
In a very boring class bend over and pick up invisible objects from the floor. Build an invisible structure carefully balancing each invisible object.
Memorization and regurgitation
Memorize word for word a long section of the speaker's words. Then raise your hand. When called upon. You go, "Did you say blah blha bablah." They tend to be very perplexed and confused.
Say, "That's not true" or "Not exactly" You may also quote non-existent rules, laws, and regulations.