Common Dutch slang: tof (cool/great — very widely used), waanzinnig (crazy — used positively: that is waanzinnig! = that is amazing!), knetter (crazy — knettergek = crazy), maf (weird/odd), te gek (too crazy — meaning excellent), geinig (funny/amusing), stom (stupid — mild), vet (fat — used as slang for cool/awesome in youth language), chill (borrowed from English, widely used).
Informal filler words: nou (well/so — used constantly), even (just a moment/just), gewoon (just/simply — overused: ik ga gewoon naar huis = I am just going home), eigenlijk (actually/basically — used as a hedge), zeg (say/I mean — discourse marker), snap je (you know?/understand?), weet je (you know?), toch (right?/isn’t it? — seeks confirmation). These fillers make speech sound natural.
Colloquial phrases: lekker bezig (nice going — can be sarcastic or sincere), niet zeuren (stop complaining), doe normaal (act normal — Dutch phrase for calming down or fitting in), ga weg! (get out of here! — expressing disbelief), echt waar? (really? is that true?), dat meen je niet (you cannot be serious), prima (fine/okay — understated approval), best wel (quite/pretty — best wel moeilijk = quite difficult). Slang varies by region and age group.