Does anyone know what this means?

I've always understood it to mean that they are in a gang and have killed someone. Each tear represents a life they have taken.

I have been told that teardrop tattoos mean they are depressed!

the tear drop tattoo is a symbol for some one who has been in jail every tear drop represents 1 year they spent behind bars for the tears their mothers have cried.

It depends. Sometimes each teardrop signifies each person they've killed, and sometimes it signifies each year they've been in prison.

When Tookie Williams, co-founder of the Crips, was put to death a few months ago, he himself said it stood for every life they had taken.