cabecear = to shake one's head

cabeceo = I shake my head

Shake Your Head was created in 1983.

You head hurts when you shake it because your brain hits against you skull

One could reply with a hesitant shrug or very slowly shake their head.

Acronym for 'shake my head' or 'shaking my head.' Usually used when someone finds something so stupid, no words can do it justice. Sometimes it's modified to 'smfh' or 'smmfh' by those that prefer profanity in their internet acronyms.