Sukhoi Su-20/22 Fitters always have these distinctive markings on the sides of their noses:
I assume these are hazard warnings for the jet intake. Curiously, though, I've never seen a photo of any other type of Soviet/Russian jet with this or any other style of intake hazard marking -- not even the MiG-21, which has a similar intake design that sits at about the same height above the ground.
Why is this? Is there something about the Fitter's engine intake that makes it especially hazardous to ground personnel?