Crab mentality or crab in a bucket syndrome is when a person makes an effort to pull down another person out of jealousy of his success. This is the root of all evil. This happens in our daily lives. The same way, it also happens in search engine optimization.
There are many ways on how to execute this. Here are some of them for you to be familiarized and help protect your website from culprits:
The Third Party
This is when another website puts your link in their page but looks really spammy. This is usually caused by porn sites. This can have a drastic effect on your rankings when search engines notice these links. To be able to avoid in getting in this kind of situation, you should constantly keep track of your inbound links. Google webmaster central can do the work for you. If you already know the culprit, send a message requesting to take down your links.