Hook up behringer 180 and crate 100
 

Would it be ok to do this or stupid? How would I do it what's safe way to do it with out fn my stuff up

If I'm correct, Behringer 180 is a bass combo, Crate 100 is a guitar head .. why would you like too hooke these two?
But if you really want to do it, you would have to find the wire in Behringer that goes from amp to speaker and uplug it (or cut and solder on a connector). Than you only have to conect Crate head and Behringer speaker with a speaker cable.
But I still don't see any sense in it. It won't get any louder or something like that...

What is the goal?, and explain each piece of gear. Combo amps? heads? Tell us the whole thing first, with a goal.

Each is a combo the crate 100 is a 100 watt amp combo

I guess I'm not really looking for sound cause behringer is loud enough maybe just a look