It’s offensive ONLY if the “victim” takes offense.
I once worked in an office in which there was me, one 60 yr.-old guy (
my only competition 
) and four women – one of them a hottie.
The things that were said and done…
You could never offend anyone in that office!
I heard comments about my butt, on average, once a day.
I twice even had it grabbed, and thought it was hilarious!
So long as it wasn’t the old guy grabbing it.
The hottie once lifted her shirt to reveal her beautifully bra-clad bosoms and dared the old guy to grab those bad boys. He did!
Everybody had tears of laughter rolling down their cheeks.
The only one offended by that episode was me.
Why was
HE getting all the fun?
Sadly, it seems that fewer and fewer people are relaxed and secure enough to enjoy shenanigans like those.
On the flip side, there are fewer people who can pull off those stunts with enough class, discretion and respect so as to not to offend.
When either side goes too far, it's not fun anymore.

We had a great time because we were all on the same page, and knew how to take it.
I’ve never worked in a place like that before or since, and doubt I ever will again. Those were some really fun times.