Phil’s panicked reaction to Denise’s advances is a classic example of his awkwardness and Claire’s "I told you so" intuition.
Manny’s reaction to the truth shows he is often more mature than the adults in the room. Where to Watch [S1E17] Truth Be Told
Phil reconnects with his high-school girlfriend, Denise (played by Judy Greer), on Facebook and invites her over. Claire is convinced Denise is still into Phil, which Phil obliviously denies—until Denise makes a move on him in the pantry. Phil’s panicked reaction to Denise’s advances is a