hmm, can’t say i’ve heard 90% used seriously in the last 13 years of school/college i’ve been in!
Probably the most used word right now is ‘brilliant’. Combined with sarcasm it can be used as a response to almost anything!
‘LAD’ (spelled with caps) is also popular, google ‘LAD bible’ to find out why..
These days most phrases are one liners from shows and films. Anything from the inbetweeners, bad education, top gear, etc goes.
oh, and when you’re riding with a group of mates the same age, you have to quote lines from ‘sh*t mountain bikers say’ at every opportunity for the lolz 😛