Sick = muito bom, excelente
ex.: That party last night was sick
Pay attention because sick also to is "doente", but here like slang is really good.
Nick = roubar
ex.: OMG, someone nicked my car.
Tad = uma pequena quantidade
ex.: I always drink tea with a tad of milk in the morning.
Fit = atraente
ex.: Have you seen the new girl? She is so fit!
Spud = Batata
ex.: Do you prefer spuds, rice or pasta?
Buck = Dollar
ex.: Could you borrow me 10 bucks?