Chalking is when a student uses chalk to write a particular message on classroom blackboards. A less common version is using chalk to write messages on the ground or walls. These writings are usually advertisements for a group function or event. It is not permitted under UC Davis regulations, but students tend to do it anyway. There are also questions as to how vague the regulations are, as they do not define chalking. As has been pointed out, does this mean that UCD Gymnasts can't use chalk on their hands?
This video depicts an October 2011 conversation between UC Davis police officers and UC Davis students regarding chalking outside the MU.
In 2007-02, a student at Penn State University appeared before a judge in a Pennsylvania court of law, and it was ruled that chalking wasn't illegal due to lack of damage caused. In her case the chalking had been done on doors and outdoor columns. Is there a more relevant/local case that establishes the legality (as opposed to UC Davis policy) of chalking?
The best time to go chalking is around 6am, since chalkboards are often cleaned off at night. Most of the buildings open around 6, so it gives you about two hours before any classes start to get your message down. While it is considered rude to erase chalks from current events, no one is offended if you erase their chalk from a past event.