  As gamma-ray burst (GRB) jet drills its way through the collapsing star, it
traps a baryonic cork ahead of it. Here we explore a prompt emission model for
GRBs in which the jet does not cross the cork, but rather photons that are
emitted deep in the flow largely by pair annihilation are scattered inside the
expanding cork and escape largely from the back end of it as they push it from
behind. Due to the relativistic motion of the cork, these photons are easily
seen by an observer close to the jet axis peaking at
$\varepsilon_{peak}\sim~few \times 100 keV$. We show that this model naturally
explains several key observational features including: (1) High energy power
law index $\beta_1 \sim -2 {~\rm to~} -5$ with an intermediate thermal spectral
region; (2) decay of the prompt emission light curve as $\sim t^{-2}$; (3)
Delay of soft photons; (4) peak energy - isotropic energy (the so-called Amati)
correlation, $\varepsilon_{peak} \sim \varepsilon_{iso}^m$, with $m\sim 0.45$,
resulting from different viewing angles. At low luminosities, our model
predicts an observable turn off in the Amati relation. (4) An anti-correlation
between the spectral full width half maxima (FWHM) and time as $t^{-1}$. (5)
Temporal evolution $\varepsilon_{peak} \sim t^{-1}$, accompanied by an increase
of the high energy spectral slope with time. (6) Distribution of peak energies
$\varepsilon_{peak}$ in the observed GRB population. The model is applicable
for a single pulse GRB lightcurves and respective spectra. We discuss the
consequence of our model in view of the current and future prompt emission
observations.
