I had a different version when I thought of this strip, but I didn’t want to make Ted filthy.  Well, he is filthy, but not the unhygienic kind of filthy.  The scrapped version was suppose to be like this:

Greg: “Who did this?”

Ted and Tag point at each other.

Greg looks at both of them, but more so at Tag skeptically, “C’mon, fess up.”

Ted then looks ashamed, “Sorry.”  Greg looks horrified.

But yea, that was the first idea.