Can guys get hair extensions?

Hair is hair. You can get extensions or do anything to your hair that a girl can do.

Yeah, but I suggest you don't leave them on your hair for too long!

Traction alopecia is hair loss that occurs as a result of continuous pulling of the hair. Pulling may occur from hairstyles such as tight cornrows, plaits or braids with or without extensions, weaves, ponytails or even hair rollers or curlers. Natural hairstyles can also lead to traction alopecia as well. Long heavy locks and tightly coiled twists can lead to traction alopecia. The hair loss associated with traction alopecia typically occurs at the frontal hairline, at the temples or the area of the scalp above the ears. It may also occur at the posterior hairline.

“Any style that causes too much tension and traction on the hair, such as braiding with artificial hair weaved in, can possibly lead to scarring hair loss,” says study author Angela Kyei, MD, a dermatologist at the Cleveland Clinic in Cleveland, Ohio.

If the guy has the money to pay for them and to get them installed, why not?

I guess, but you'll look stupid.