Just curious. What would happen if, instead of using trumpet mouthpiece, we use reed mouthpieces (oboe, clarinet etc) on a trumpet. I know the hole will not fit well but, will it still be in tune?

Get a bassoon reed and then wrapped tape or something around it to get it to fit your leadpipe. Or make some kind of adapter.

I think you will be surprised.
It's not something that you will want to have in the concert band, but it is fun to play with. I've done a lot of double reed playing on my Horn in college.

Sounds quite scary to be truthful.

lol its true...stick an oboe reed in a french horn or a trumpet it sounds really weird and funny...LOL

or a bassoon reed in a trombone...i think thats on youtube.
http://www.youtube.com/watch?v=K3mMlIgbCsU

oh ive done that with a clarinet mouthpiece..you kinda get one tone and a few semi-tones around it...its pretty weird...plus it sounds awful...LOL