  The origin of the recently discovered new class of transients, X-ray
quasi-periodic eruptions (QPEs), remains a puzzle. Due to their periodicity and
association with active galactic nuclei (AGN), it is natural to relate these
eruptions to stars or compact objects in tight orbits around supermassive black
holes (SMBHs). In this paper, we predict the properties of emission from bow
shocks produced by stars crossing AGN disks, and compare them to the observed
properties of QPEs. We find that when a star's orbit is retrograde and has a
low inclination ($\lesssim 40^\circ$) with respect to the AGN disk and the star
is massive ($\gtrsim 10$ $M_{\odot}$), the breakout emission from the bow shock
can explain the observed duration ($\sim$ hours) and X-ray luminosity
($\sim$few$\times10^{42}~{\rm erg~s^{-1}}$) of QPEs. This model can further
explain various observed features of QPEs, such as their complex luminosity
evolution, the gradual decline of luminosity of the flares over several years,
the evolution of the hardness ratio, the modulation of the luminosity during
quiescent phases, and the preference of the central SMBHs to have low masses.
