From Academic Kids
The tambourine is musical instrument of the percussion family consisting of a single drumhead mounted on a ring with small metal jingles. It is held in the hand and can be played in numerous ways, from stroking or shaking the jingles to striking it sharply with hand or stick or using the tambourine to strike the leg or hip. It is found in many forms of music, classical music, Roma music, Persian music, gospel music, pop music and rock and roll. The word tambourine finds its origins in the Middle Persian word tambūr "lute, drum" (via the Middle French tambour).
The thumb roll
By stroking a thumb (or sometimes a finger) across the head of a tambourine, a sustained roll may be produced. The thumb is often wet slightly by licking it to increase the friction immediately before performing a thumb roll. Although a shaken roll is often used for longer rolls, the thumb roll is particularly effective for shorter rolls. It can be sustained by moving the thumb in patterns such as figures-of-eight across the head. However, since the tension across the head varies, this requires the player to vary the pressure applied to the head as he moves his thumb.