Fatheads making sudden movements (5)

I believe the answer is:

jerks

I'm a little stuck... Click here to teach me more about this clue!

'sudden movements' is the definition.
(I've seen this in another clue)

I can't explain the rest of the clue.

(Other definitions for jerks that I've seen before include "Exercises; fools (slang)" , "Jolts" , "Yanks'" , "stupid people" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app