I have lots of whimsical doggie stamps, so that's what the guys in my life usually get!
I use masculine colors, plaids, stripes, etc. and try to put a funny verse in them, sometimes with my computer.
My favorite these days is a cute dog on the front, a happy birthday sentiment, and inside - "A tail has been wagged in your honor."
And just recently, my son-in-law had one of those milestone birthdays. I used the verse - "Your birthday is no day to feel old" on the front. Then inside, "Wait, yes it is."
Bugga in OK
"Be kind whenever possible. It is always possible." Dalai Lama