A disco freak is someone who is an outrageously disco-tastically freak-ishly florridly crazy clothed person thing. It is primarily a state of being but is helped by having frizzy neon hair, clashing colours, yellow eyeshadow, huge earrings and shoulders pads. Shell-suits are also common.
See also: David Bowie rick astley and cyndi lauper
1) Cor Blimey, Sarah those pants are sooooooo discooooo freaky!
2) David Bowie...yeh..disco freak.
3) Sarah's hen party? DISCO FREAK! Oh yes.