Underspeed. Conjugate like any other verb. Jeff undersped the whole time we were in Israel, going 80 kph when the posted limit was 60 kph. Krishnan and I mocked him severely when even a bus passed us at about 100 kph.
When you and your friends are passing around a bong, and Y'all smoke the top layer of the weed. The Underweed is all the smokable weed under the burnt top layer in the bowl.