Wow, this thread is awesome.
My scariest would have to be a river crossing. Out on an old military base, saw signs saying "4x4 tactical vehicles only". Did on stream crossing no problem, wheeled around, etc.
Came to another stream crossing that looked nearly identical to the first...but something was off. My friend says "dude, it's the same one, just go." I questioned him a few times and he called me an idiot, so...
Into 4Lo and off we go. Front end just sinks! Luckily I had good forward momentum, water was running up over the hood, fan was clapping in the water, etc. JUST made it out, water marks up to the door handles.
SOMEHOW I didn't hydro-lock! Thanks god. Hahaha. Never listened to him again.