Aside from, you know, safety and professionalism, I experienced another great reason to not gum up Guard yesterday. Some poor guy checked in with Ops on Guard, to which my CA immediately responded with a hearty "Guuuuuaaard" call. This of course prompted about 30 sec of witty banter between other aircraft, which we snickered to. Not too long after we got a frequency change, and when the CA checked in on the new freq another string of witticisms began immediately.... because he'd checked out on Guard and then checked in again on Guard. Coffee damn near came out my nose I was laughing so hard. Play with Guard and you might burn yourself!