The escape velocity on Mars' moon Phobos is about 11 m/s, or 25 mph. The body's mean diameter is 11 km (6.8 mi). Its smaller cousin, Demos, with a mean diameter of 6 km (3.7 mi), has an escape velocity of only 6.9 m/s (15 mph), meaning that you could probably jump right off it if you tried hard enough.
