What makes a Swimsuit a Swimsuit?

From BriefTales ShortNote 9/2/2008

So... what makes a swimsuit a swimsuit? Is it the fabric (spandex, lycra)? Is it the cut (fly vs. no fly)? It can't be the style (bikini, thong, boy short or boxer trunks and briefs) because they were all present. And, would it be safe to say that Swimwear isn't worn as underwear but underwear can be worn as Swimwear? If that's the case, why is Joe Snyder so popular as underwear and Swimwear (check out the new bulge thong)?

Several years ago I rafted in upper Wisconsin. The rafting company was very busy that morning and launching everyone was an orchestrated effort. Groups, parties, families all lined up to launch. With such speed, all of the rafters either came in rafting gear or quickly changed. I actually saw two guys, in separate groups, just drop their pants and launch out rafting in just their tightie-whities.. I believe they were Calvin Klein. In this case, everyone who saw them was aware they were rafting in their underwear! Maybe years ago when men's underwear was boring, plain and white, there was a pronounced distinction between underwear and Swimwear. But today, can it double as both? Have you ever worn underwear as Swimwear? Did you do it for convenience or was it a planned event? What are your thoughts?
Please send your comments. Just be sure to reply. Your thoughts are appreciated.

Hope to hear from you soon.

Dave