Both

They headed to Goten's house first, since Chi-Chi was at home and was therefore the much easier target.

However, upon entering the house...

"M-Mom?" Trunks asked upon seeing Bulma sitting on the couch and chatting with Chi-Chi. "What are you doing here?"

"I got off work early so I decided to pay Chi-Chi a visit," Bulma said with a shrug.

"Hello, boys," Chi-Chi waved from the kitchen.

Goten and Trunks looked at each other and shrugged. Having both their moms here would work, but they decided to start with Chi-Chi since she was their initial target.

"Hey, Mom," said Goten. "Could you please..."

"Please let us see you in your underwear?" Trunks suddenly called out. Goten stared at him in shock.

Chi-Chi smiled. "Of course, Trunks, since you asked nicely."

She proceeded to strip out of her dress and went back to making lunch in her plain black bra and panties.

Goten looked to Bulma. "Are you okay with this?"

"Of course," Bulma said. "Trunks did ask nicely, after all."

Chi-Chi brought the food into the living room. "Goten, go to your room, please." she said. "You can't see me in my underwear."

"Fine," Goten said. "Miss Bulma, would you please..."