If you want to celebrate in Second Life, start with an SL Marketplace search for Towel Day (like this search) and you'll find two towels specifically for the holiday plus a rather nice lot of ordinary towels. First to appear, at least for me, is the towel I've been floggin' by bloggin' for the past few days, the one I made (get yours here, ladies, for free).
|Apparently are events in Second Life to celebrate (like at Ye Olde Terrier's Inn, SLurl). I've suggested it as a theme at the Isle of Lesbos, but I hadn't heard back from anyone. Try Search yourself? Or the Destination Guide?|
You can also visit Milliways, the Restaurant at the End of the Universe (SLurl) from 12pm SLT (until The End, I guess). Look for the group in-world for more information in Past Notices.