I want to do a dobbel flip, but I dont know how i do it.
Can anyone help me?
What’s a Dobbel flip?
double crankflip?
Yes!
Any tip?
Stating the obvious here, but do just like you do a normal crankflip but spin faster and/or jump higher off the uni. If you’re nowhere near, and can just barely manage a regular crankflip, go back a few steps (the steps outlined in Shauns crankflip tutorial for example) and practice your spins with foot-/zeroplants. (Note that I cannot do a double crankflip (or a single for that matter) myself, I’m just applying reason and common sense 
)
One of the most important differences between a doubleflip and a crankfllip is that with a doubleflip you pull up on the seat much more. All the other advice I can give you is do your best to keep the unicycle under you and just kick hard.
I suppose you can also try doing it 2 handed. It is well known that it is easier to kick something 2 handed, although it doesn’t look quite as good.
Its a little weird when u want to learn double flip when u just learned crankflip and can just flip up 1 pallet and 180 flip…