A name defining a person who bears a great resemblance to a rat, or other similarly scurrilous rodent. Generally, they feature an elongated nose, fur where there shouldn't be any, and a high pitched, squeaky noise, accompanied by the clawing of anything it doesn't approve of. Furthermore, the person in question usually suffers from a terrible form of malodour, usually known as reek
Generally, a "Tyam" also has problems constructing basic sentences and words, usually mispronouncing them as if slurred, such as "I say, do you think I smell?" being spoken as "YOU SAID I REEK!"
"God, you're such a Tyam!"
"What? You.. you said I REEK! You TWAT!"