This term defines an especially hairy human male. Often attributed to Italian men.
Root Words - Shag : long, thick carpet or hair, usually messy and tangled. Nuts : Balls.
Singular Plural - Shagnuts : referring to a pair of testicles encased in a very hairy nutsac.
Guy # 1 : Fuck, dude. You are one hairy bastard. Your arms look like a Wookie's.
Guy # 2 : Yeah, I was able to grow a mustache when I was 11 years old.
Guy # 1 : You fuckin' shagnuts.