I took the liberty of copying and pasting the conversation, as I wanted to reply to each verbal sally. These are my observations only. I am not a counselor, nor do I play one on TV.
DM: So when I was outside fixing the fence, I saw a car with a bumper sticker that said "I don't just hug trees, I kiss them, too." Nothing wrong, teasing or PA about this statement. It sounds like you were just making an observation.
Brother: You mean while DB was inside putting the groceries away? -grin- Brother was needling DB about doing a "womans" job or at least the more feminine job while you were doing the "mans" job.
DB: Yeah, that she bought with my money. I think DB was just replying to brother, to show that he was "bringing home the bacon" or doing the "masculine" job. I don't believe he intended to hurt you with this remark, he was defending himself to his brother.
DM: Yeah, but you didn't have to go shopping (something we both hate), so you got off easy. DB's statement hurt you when he told his brother that you had used his money to buy the groceries. You have guilt associated with not having a tax paying job right now, so you are trying to show that you do contribute to the household. But this shifted the pseudo argument from DB's brother to you.
DB: I've had to go shopping lately. DB is now replying to your saying he "got off easy", he is now directing his anger/frustration at you instead of his brother. DB is still trying to prove that he does his fair share in the household.
DM: Yeah, but when was the last time you went alone for the both of us?Your reply because it's bothering you about your contributions to the household. You both have left the realm of teasing and moved to PA comments/arguing.
DB: Like a year ago -chuckle-...-pause- Well when was the last time you had a job? DB wanted to cut you down to size a little. First his brother was needling him about his masculinity, now you have picked up the baton and won't stop needling him. He struck back at you in a way that he knew would hurt you.
Does brother often needle/tease DB about your rel@tionship or in other areas? Did they grow up in a family that do this often? When brother is teasing DB it may help your rel@tionship with DB if you stayed out of it. I believe that DB was only responding to his brother with the "my money" comment. I don't believe he meant to hurt you or even tease you. However, you turned his attention to you when you jumped in with the "got off easy" and DB felt he had to defend himself to both his brother and you.
Surianne has the right idea. Try to not tease each other for a week and see how it goes. If he doesn't want to/can't, you stop teasing him with other people or when anyone else is around. If DB continues to draw you in or make remarks that hurt you, it will be time for a rel@tionship talk.