concocter

Vois ce que tu peux concocter.

See what you can come up with.

Il nous faut concocter un plan.

We must come up with a plan.

Que vont-ils concocter d'autre ?

What will they think of next?

Comment peuvent-ils simplement concocter un truc pareil ?

How can they just make up stuff like that?

Tu es en train de ricaner comme un petit galopin qui vient de concocter un mauvais coup.

You're sniggering like a mischievous little brat who's just cooked up a dirty trick.