Quote:
Dude standing with his girlfriend enjoying a drink.
His friend comes over: "What's up... OMG dude you smell like you haven't had a shower in years!"
Dude responds:

Friend: "I don't want you looking like you live in the streets like a homeless man."
Dude responds:

Yea
Friend: "Take a bath. If you want you can use my urinal to wash yourself."
Dude: haha
Friend > Dude
See this is where you and me differ. I read what you're written and think Dude > Friend
It's like that Back to the Future II movie where the main character can be pushed into doing absolutely anything by being called "chicken". Who wants to be that guy?
Assuming you don't have an actual hygiene problem, someone saying the stuff above would be funny. I would expect to laugh along, and I would expect the girl to join in, and a good time had by all.
If you do feel the need to respond, something like this:
"What's up... OMG dude you smell like you haven't had a shower in years!"
"I don't believe in them"
"I don't want you looking like you live in the streets like a homeless man."
"That's just my look"
"Take a bath. If you want you can use my urinal to wash yourself."
"Very kind"