0:00–0:13 — Intro loads the contract

The opening does not wander into the song; it snaps the fast band pattern into place and lets the vocal arrive onto an already-moving track. By the time Underwood enters on “Last night,” the form has its runway.

0:13–0:57 — First verse proves the confession/refrain shape

The first vocal section narrows from a night out to the hook. The verse lines carry the story in quick steps, then the chorus lands at 0:33 with the first full payoff: she does not know his last name. The music matches the lyric’s momentum by refusing hesitation; the joke is delivered inside a steady forward drive, not as a pause for embarrassment. The “Woo!” after 0:57 works as a reset button.

1:00–1:48 — Second cycle repeats, with more evidence

The second verse reloads the same structure rather than changing it: club exit, car detail, warning sign, blame shifted onto Cuervo. The chorus returns at 1:24 and confirms the form’s main bargain: each verse adds a worse decision, each chorus cashes it in with the same refrain. Nothing needs to open wider yet; repetition is the point.

1:48–2:29 — Break and twist section

“Here we go!” sends the track into an instrumental carry before the vocal comes back at 2:04 with the Vegas aftermath. This span changes the section job: it is no longer just another drunk-night report, but the setup for the hook to mutate. The ring, the escape plan, and the Pinto all hurry toward the turn.

2:29–3:19 — Chorus changes the hook’s ownership

At 2:29 the chorus returns, but the pronoun flips: she does not know my last name. The band keeps the chorus machinery intact, so the lyric does the formal damage. The repeated “What have I done?” after 2:53 extends the refrain into a post-chorus, holding the consequence in place before another hook return at 3:00.

3:19–3:59 — Vocal lift, final reprise, hard finish

The last stretch spends its remaining time on release and confirmation: ad-libs, another clipped pass through the pickup line and regret line at 3:41, then the final “last name” lands before the track cuts off. The ending does not solve the story; it stops after the hook has changed from punchline to paperwork.