Keep it civil, do not flame or bait other users. If you notice anything illegal or inappropriate being discussed, contact an administrator or moderator.
You aren't allowed to upload any images with third-party watermarks to Gelbooru. The only person who can watermark an image is the original artist or their publisher. "Original artist" refers to the person who drew the original image; even if you've heavily edited an image, you aren't allowed to watermark it when you upload it to Gelbooru unless you drew the original version.