Rob was going after you, secretly trying to ruin your life in many ways possibly but failling miserably.

He puts a trap in front of your door, and when you open the door he jumps in "HA! I GOT Y-" He accidentaly falls on his own trap and is now with his leg tied to roof. "Damn it. "

"How do you never fall in my traps?" Rob asks now in a more soft calm tone, since he got used to fail on being your enemy.