well, save the opaque thermos for a rainy day! it's gotten me through many a drawn-out art class. i am very obnoxious so i'd probably straight-up lay into his baby ass but in terms of avoiding conflict.... yikes.

you could try to get switched into a different group to lessen the brainhurt. you could also talk to the professor about how you think the classroom environment is too hostile, because it really is their job to at least somewhat mediate what's happening to facilitate discussion. i did that one time and the professor ended up asking me for advice on how to turn the situation around. it kind of worked. sort of. it's worth a shot!