I was in a fraternity and there was never any sexual stuff that went on during the regular pledge program. There was a lot of physical hazing, like push-ups, exercises, and such, but nothing involving sex with the actives.
During our hell week, we did have to stay at the house and all sleep in the same room. They had fun with us, making us all strip down to our underwear and get into our sleeping bags in 5 seconds. Of course we couldn't do it that fast, so get dressed and do it all over again. We had to all be alike, so we all had to be wearing the same type of underwear. Most wore white briefs, so those of use who wore boxers (me), or colored briefs or bikinis (Lou, Sean, Rick) had to wear tighty whities that week.
During breakfast, sometimes the pledges had to strip down to their underwear and play around as if they were Sumo wrestlers. I never had to do that, luckily.
The last night, we were all out in some field, way out in the boondocks, and this was the only time the pledges would all have to strip down naked. There were threats of sexual stuff yelled at them, but nothing ever happened. Then they would get dressed up in a particular uniform for the rest of the night. So no overt sexual stuff, just some minor nudity.