“Day-to-day resistance” was the most common form of opposition to slavery. Breaking tools, feigning illness, staging slowdowns, and committing acts of arson and sabotage—all were forms of resistance and expressions of slaves’ alienation from their masters. One North Carolina cook later recalled: “How many times I spit in the biscuits and peed in the coffee just to get back at them mean white folks.”
Source: Digital History at http://www.digitalhistory.uh.edu/black_voices/voices_display.cfm?id=25
In addition to everyday forms of resistance, slaves sometimes staked more direct and overt claims to freedom. The most common form of overt resistance was flight. As early as 1640, slaves in Maryland and Virginia absconded from their enslavement, a trend that would grow into the thousands, and, eventually, tens of thousands by the time of the Civil War. During the early years of slavery, runaways tended to consist mostly of African-born males.