Green’s Dictionary of Slang

a general term of abuse; an incompetent, an inadequate; also as v., to move in a clumsy way.

1977		L. Bangs in Psychotic Reactions (1988) 257: A kid moving through the crowd in a jagged mechanical pivoting careen [...] not seeing me as we collide and he spazzmos on.
1998		I. Welsh Filth 298: There’s a white Nissan Micra on a double fucking yellow line [...] Where are the traffic spazmos?
2001		OnLine Dict. of Playground Sl. 🌐 spack, spaz, spazmo, spacker, spanner, spadge n. derog. [...] 2) An excessively stupid or unpleasant person.