Okay, this may sound weird, but Donald Duck probably has been seen without any clothes on. I think the first time he was seen without anything on was "On Ice" when Mickey undoes Donald's sweater and Donald pops up out of the water where Goofy was fishing for fish and clobbers Donald, thinking that he was a fish....And Donald was only wearing a hat. But as for the first comic that Donald Duck was seen in his Birthday Suit was probably in a comic strip released by Al Taliaferro in August 2 of 1938 where he bathes in a cop motorbike.
I may be wrong here.
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