In this comic, we flashback to the boys early days in the manor, hanging out with Webby. Of course at this point, Webby has been living a sheltered life in the manor so she wouldn't be as aware of social norms just yet. (to be fair, she was never shown to own a swimsuit in the actual show)
 
(This comic was done by an artist who wishes to stay anonymous and is uploaded with their permission)

PLEASE NOTE: this piece contains nudity but it is intended to be depicted in a non sexualised manner
 
DuckTales belongs to Disney