Ever wish you were one of the first people on the Internet who secured obvious domain names — like Fun.com, for instance? For the people who thought a little, well, naughtier, it paid off big time. Business Insider searched through the domain name resource DN Journal and curated a list  of the most expensive domain-only sales. As it turns out, the top ones probably won't surprise you.
1. Sex.com  (NSFW, obviously)
Sold in 2010 for $13 million, Sex.com made it into the Guinness Book of World Records for the highest domain-only sale in history. Wowza.
2. Fund.com 
Fund.com went for $9,999,950 in 2008 when it was bought in straight-up cash.
3. Porn.com  (NSFW, obviously)
In 2007, Porn.com sold for $9.5 million and was the biggest all-cash transaction for a domain name at the time.
4. Diamond.com 
So that's what $7.5 million got you in 2006. Naturally, an online jewelry retailer, Ice.com, scooped up the name.
5. Slots.com 
Gambling-lovers should note that the name sold for $5.5 million in 2010. That's more than $1 million per letter!
For more crazy-expensive domain names, check out the rest of the list on Business Insider .