Word for something (e.g. a group of friends) being male-dominated?

"male-dominated", as in your title, is the term I'd use. Otherwise, if you're open to a slang term, you could use:

sausage-fest A party or gathering where all, or the vast majority of, the participants are male.

In the UK (and possibly Australia) you might say: My first term at university has been a bit blokey.

How about: My first term at university was estrogen-poor. Or - My first term at university was testosterone-heavy, or testosterone-dominated.

If you are looking for a quip, you could go with "man-tastic". Also, it might help inspire better answers if we could know the gender of the speaker and how he/she feels about the situation stated.

It is not terribly colloquial, but perhaps the most correct single word is

Androcentric

centered on, emphasizing, or dominated by males or masculine interests