One class I took studying at Boston University's pre-college fine art program was figure drawing. We had live models to draw. One exercise we did was to draw the figure in under 3 minutes, 1 minute, or 30 seconds with something permanent, like sharpie marker. This one was done in 3 minutes, starting with the main figure on the left and adding in the environment to the right with another one of my classmates in the doorway.
Observational, sharpie on paper, 18" x 24"