The four scariest phrases ever heard in the military:

The E-1 who says, "I learned this in Basic Training..."
The O-1 who says, "Based on my experience..."
The E-5 who says, "Trust me, Sir..."
The E-9 who chuckles, "Watch THIS sh*t..."
Even more scary:
A Pfc with a badge.
A 2nd lieutenent with a map