The one and only time me and my girlfriend did diaper humiliation was during one week of role play and she was being an absolute brat, screaming, yelling, throwing toys, throwing diaper supplies and her used diaper around during changing along with kicking so instead of spanking her butt raw I decided to say hey lets go on a car ride which we do from time to time during role play, we don't stop anywhere just drive around.
Well I drove to another towns Walmart about 30 minutes away, she had on a doubled up Lil Monster, one was soaked and I wasn't dealing with another diaper change, she had on a t-shirt and pants that covered her diaper but the bulge was still noticeable and her shirt was pretty long and went down over her butt, but still you could see the bulge if you looked for long enough and I told her since she wasted all the powder during her last diaper change we needed more and I wasn't leaving her in the car and if she refused to get out then I was going to duct tape her diaper closed and not change her for the rest of the week (it was Tuesday role play at the time ended on Saturday) and spank her 3 times a day, so we walked around Walmart for about an hour and my user name is DiscreetDL for a reason, we don't like people finding out about our love for diapers unless they're also DL's, and before the trip I gave her a bottle of Strawberry milk, her favorite, with a little added fiber powder which kicked in while we were shopping, she was able to hold it in and I knew she was so I decided we needed some new movies and while browsing she messed her diaper, no one else was around being early in the day so I patted her smelly butt and said "someone needs a change, lets go to the bathroom and get you cleaned up", her face was already red the entire time so far and some how it got redder and she whispered to me "Please don't change my dirty diapee here daddy" (we agreed to not break character during sessions), my reply was "Are you going to be a good girl and stop being a brat?", she said yes, I still took her into the bathroom but let her put on perfume and dump the last of our powder down her diaper, we checked out at a self checkout and left, the ride home was quiet and a bit smelly and she got a fresh diaper at home and I told her "I'll deal with bossy, fussy, and whiny not bratty", at the end of the week I asked why she was so bratty and she wanted to see what I would do to punish her.
So basically have her double you up in some thick diapers and lead you around a store all the while having the urge to go and use your diaper.