You could call them out on what they are doing (most guys respond by just calling you a b*tch, but it is so satisfying making them uncomfortable back).
You could flip them off.
Pull out your phone and obnoxiously record them and tell them you'll take it to the police (whether or not you do is a different story)
Pull out some pepper spray and ask them if they want things to get heated.
Or ignore them.
I only retaliate if I'm in a rather public area or can quickly get help.
As crappy as it is, sometimes you can't respond and risk escalating the situation if you're on a backroad or other isolated area.
I've lived in enough places where I go out for runs and wonder, despite having pepper spray and my phone, if that will be the day I get sexually assaulted or beaten up.
Life as a woman running. I never get use to it, more learning to let it roll off your back.