Hands in pants constantly!!

[Lilliput]

I am so sick of my 8yr old ds with his hands down his pants fiddling with his penis. It is constant, at meal times, watching telly, playing, chatting.....
I am always telling him to stop but it is an absent minded habit now. How do I get him to stop?

Give him space to do it at certain times. Other times like meal times are then an absolute no? Ds is nearly 4 and fiddles a lot but not allowed at bedtime and we try and keep him busy so he doesn't do it (as opposed to telling him not to).