It is all in the FAQ section here
but the general rule is PG13
Q: Are adult images suitable here?
A: Sorry, but they are not. Anything posted to our site that is offensive in nature will be removed, including nudity. If the incident appears to be intentional, we hold the right to use your IP address to contact your ISP for further investigation. These rules also apply to those who abuse obvious copyright rules. We try very hard to abide by all written and non-written laws and regulations.
and this one is handy to remember
Q: Can I use copyrighted material in my entries?
A: Not unless you contact the proper owners of the image and obtain permission. Contact them first, you may be surprised at how many will give you the OK.
hope that helps