An
offensive extremely racist term for a person of Scottish origin.
Calling someone a "Dethy" is a
collective way of calling somebody a rapist, pedophile or someone with a strong yearning or desire to have
sexual intercourse with a person under the age of 18.
In several places in the UK it is considered as bad or vulgar as using the word "Nigger" to describe a colored person.
It is often used in the same context as "Gay", meaning it is often used as an insult as opposed to actually describing somebody in this context.