slightly obscure this one, but was nevertheless widely used for a while in central london. it means to chill, relax, often along with smoking weed. derived directly from cotch, its root is interesting... the mathematicians amongst you will know that hyp(cos) is written 'cosh', and pronounced 'cotch'. this is trigonometrically equivalent to one over hyp(tan), or '1/tanh', pronounced 'tanch'. most people are unaware of this - its nevertheless used widely.