What kind of bung are you using? The solid rubber ones you can fit a 3/8ths tube into, and yes, just make sure everythings wet with sanitizer and stick it right in there. I'll leave any teenage innuendo out this ;-)
If you have one of the universal ones like this:
get a 1/2" tube and slide it over the nipple in the middle.
Same deal, just push it on there. Both hoses will seal. There won't be a ton of pressure in your fermenter unless the blowoff tube gets clogged, which CAN happen in a solid bung and 3/8" tube in my experience, but the 1/2" tube on the universal bung has never steered me wrong.
Lastly, if you have a hood, you can use either size, just stick it on the nipple of the appropriate diameter.