Spyro

Origin: Valve's video game hit Team Fortress 2 - A team based capture the flag style first person shooter. Players are allowed to choose from different classes of soldiers to participate in battle. One attribute of the spy is that they can disguise themselves as any class of the opposing team.

Definition:
When a friendly teammate spots a disguised spy as a Pyro.

Horus says "Watch out team, we have a spyro running around, see if you can frag him."