  arped disk galaxies are classified into two morphologies: S- and U-types.
Conventional theories routinely attribute both types to galactic tidal
interaction and/or gas accretion, but reproducing of U-types in simulations is
extremely challenging. Here we investigate whether both types are governed by
the same mechanisms using the most extensive sample of $\sim$8000 nearby
(0.02\,$<$\,z\,$<$\,0.06) massive ($M_{*}/M_{\odot}$\,$>$\,$10^9$) edge-on
disks from SDSS. We find that U-types show on average bluer optical colors and
higher specific star formation rate (sSFR) than S-types, with more strongly
warped U-types having higher sSFR. We also find that while the S-type warp
properties correlate with the tidal force by the nearest neighbor regardless of
the environment, there is no such correlation for U-types in groups/clusters,
suggesting a non-tidal environmental could be at play for U-types, such as ram
pressure stripping (RPS). Indeed, U-types are more common in groups/clusters
than in fields and they have stellar mass, gas fraction, sSFR enhancement and
phase-space distribution closely analogous to RPS-induced jellyfish galaxies in
clusters. We furthermore show that the stellar disks of most RPS galaxies in
the IllustirsTNG simulation are warped in U-shape and bent in opposite
direction of stripped gas tails, satisfying theoretical expectations for
stellar warps embeded in jellyfishes. We therefore suggest that despite the
majority of U-types that live in fields being still less explained, RPS can be
an alternative origin for those in groups/clusters.
