1. When NBC cancelled Star Trek in the late '60s a group of Caltech students went and protested with signs and chanting outside the NBC offices in Burbank.
2. In 1973 people from Dabney House hung a big "Impeach Nixon" sign on Millikan library. There's a picture of that here [1], along with a copy of the letter that the President of National Oil Company then sent to the students of Dabney informing them that he was cancelling a $1 million dollar donation because of that sign. (That would be about $7 million today).
There was an on-campus sit-in about Gaza a couple of days ago [2].
[1] https://campuspubs.library.caltech.edu/3325/1/TheCaliforniaT...