The old 737-200 has large stator vanes in front of the fan. All other models of 737 don't, they just have the fan inside the cowling, so once getting sucked in, there is nothing to hang onto to stop you. Engineers have survived a 'close encounter' with a -200 Pratt & Whitney engine because you could hang on long enough at low power pushing yourself out from the stator vanes until someone shut down. Horrible way to go, but mercifully instant.