He's referring to the pie.
House! I'm not gonna tell you a third time. Do not screw this up. Because I really don't wanna clean up the mess.
We don't know that.  Hey! Eating pie in here.
We don't know that.  Hey! Eating pie in here. [SEP] House! I'm not gonna tell you a third time. Do not screw this up. Because I really don't wanna clean up the mess. [SEP] He's referring to the pie.