I can imagine kid Goku maybe using it like a hat (kinda like in the movie Lilo and Stitch) or he might use it as a sling shot to hit the bad guys. 😆 Like I can imagine the first time he encounters a bra would be when he goes in the laundry room and then finds Launche's bra and then he starts playing with it (again like Lilo and stitch) and then Krillin would be like "Ahhh Goku do you know what that is?!!" Then he will be like "huh? A hat?" Then Krillin would be like "No you idiot!! It's a bra!! Launch is gonna kill you!!"
Anyway I only say this because I can't see Adult Goku playing with it. Just cause in that one episode with Goku, Chichi, and turtle he sees porn magazines of Roshi (both naked and bra) and he doesn't seemed fazed by it. I think he is aware of what a bra is when he's older especially being around Roshi. 👍