This guide will do what the name of the skip says. It'll allow you to skip the Tank Super Machine mini boss in 4-1.

(Disclaimer: There is no images or video. You'll have to figure it all out yourself.)

First of all, make sure it's on-screen and that you have the normal head.

Secondly, wait until it backs all the way up, then position yourself by it before turning left and jumping.

Third and finally, if you did it right, Headdy will get hit and will be on-top of the collision box.

Then you just walk off and continue forward in the level!