Teasing, under some circumstances, might actually help people bond. At least according to Dacher Keltner of the Greater Good Science Center.
Teasing can be a way to diffuse embarrassing situations, but its effect depends very much on the context and the culture. The outstanding question is how we differentiate positive teasing among friends from verbal attempts to bully. Part of the answer to this question lies in the effect: does the teasing contribute to group cohesion, or does it isolate and exclude?