Be his friend
Being a man’s friend doesn’t mean you have to slurp on meat pie and compete on how loud you can burp (although some men might like it if you join in). No, it means being on his side and accepting him for who he is, like a true friend.
What else can you do? You can put on a naughty nurse’s outfit and bring him beer. But more importantly, this is knowing what interests him, rejoicing in what gives him pleasure, and comforting him when things get tough. Be genuinely interested in his hobbies, be happy with his successes, and lend an ear when he needs to spill about something. Your being with him and your support will mean far more than any big show or acting silly ever will.