Jill of course

As Donk looked towards the sound of the door opening he saw Jill, his face grew even redder as she stood frozen, her eyes fixed on him for a few seconds before snapping and turning to Gwen.
"And what the hell do you think your doing?!" the giraffe snarled at the woman. "I would advice you to drop the curtain and allow my other customers some privacy!" the feisty reply came. Donk felt small as his young woman before him seemed able to fight for his decency more then he could in the moment! But Gwen just laughed.
"Settle down dear, I never saw anyone was in here, I was just shocked to see my nephew after all these years!" She turned to him with a smile and without warning put her hands up to his face and pulled on his cheeks. "Aw you look so much more grown up from when you were a kid." The babyish treatment mixed with his undies left an embarrassing and almost pathetic sight before Jill which made Donk want to shrivel up and die.
"Is this right?" Jill asked the donkey, "This behaviour from her isn't accepted in my store... but if she's your aunt I guess I can let it slide, but please tell her to give you some space, those brief- I mean enchanted underwear are very obvious!" Jill caught herself from calling his undies what they were as she softly scolded him, but it was clear she was more annoying with his aunt. Donk could only nod in shame, he was sure his chances with this woman were over. All the while Gwen seemed to find the situation very funny.

She allowed the donkey to get dressed and he exited the booth, discreet bag in hand and a blush still hard across his cheeks. Not helped by the sight of the underwear his aunt had picked out for herself which she was holding high and almost proudly as she strolled past into the changing room.
"Wait for me, we need to catch up" she giggled as she walked past him. With all his might Donk wanted to walk out of the store and never come back. No way would he want to speak to his aunt after she had seen his bare behind and his shameful underwear. And even worse was the idea of having to face Jill. Her knowing and custom making his embarrassing underwear was bad enough but the fact she had seen him wear them?! With his head ducked low he picked up his bag and started to walk out of the store. As he got to the door however he heard a call.
"Hey, please come over a second will you?" His heart sank, Jill. No doubt she would tease him... but he hadn't expected her to even wish to speak to him after seeing him in his underwear. It would also mean facing his aunt but he didn't want to upset Jill so against his better judgement he turned around, forcing a smile.

"Y-yes?" he asked softly as he returned to the till, unable to look at her in the eyes and instead looking anywhere else. "W-what did you need?" She smirked a bit.
"Well, since you put those on I wanted to know how I did? I have never made your... type of underwear before, a little feedback would be nice if you have time." She said, a wide smile on her face. Donk wasn't sure how to respond but luckily she did for him. "Nothing personal of course, not gonna ask how it felt around your rod, just if you liked the colour and cut of them." she said with a soft giggle. Donk could only reply with an awkward laugh at that, rod was not the word he would use for it.
"Um... w-well I guess they are nice... blue's a nice touch and... W-well they are comfy..." he was a bit of a nervous reck after what had happened but Jill seemed to understand as she leant her elbows against her counter and just smiled sweetly at him and allowed him to take his time.
"Oh wonderful, good to hear I can meet your standards... oh and take this, call it a bonus with your purchase..." She winked as she slipped him a piece of paper across the counter. Donk picked it up, expecting a gift card of some sorts but to his shock it was... a phone number? She was asking him out?! Unable to reply he just looked at her with shock which gained him a giggle from her.

Then Gwen stepped out of the changing room, fully dressed once more. A smile on her face, no doubt she had heard everything. She walked over to the counter and ruffled Donk's hair in her hand as she turned to Jill.
"Yes I'll take these on top of my other order please." she said politely but with a noticeable commanding tone in her voice. She turned to the donkey and saw the number in his hand and laughed. "Oh Dominic, if your mother knew one day you would be flirtingly with such fine catches she would be so proud!" she giggled, causing both Jill & Donk to blush, shocked by her bluntness. Before either could get a word in she spoke up. "Oh! My mother used to have a tradition, she always said a true spouse for life sticks by you regardless of who you are or what they hear about you, she would embarrass us to our crushes to see if they were worth our time... Infact I think I have some old family photo's of you running around naked as a child on my phone! Let me find them!" Both of their eyes grew wide. In an attempt to do as Jill had asked the donkey spoke up.
"N-no aunt Gwen p-please, its fine! N-no need to do that!"