Green’s Dictionary of Slang

wildo n.

[SE wild]

a wholly uninhibited or mad person.

[UK]G. Fletcher Down Among the Meths Men 50: Get them soddin’ wildos out of it. [Ibid.] 60: The wildos, the tearaways who really rev up. Always high on meths and drugs, they bug each other and will take any chance. Your ordinary meths man will avoid them.