wham 
(wăm, hwăm)
(wăm, hwăm)n.
1. A forceful, resounding blow.
2. The sound of such a blow.
v. whammed, wham·ming, whams
v.tr.
To strike or crash into with resounding impact.
v.intr.
To collide or strike with great force.
interj.
Used to indicate the sound of a forceful blow or collision.
[Imitative.]