The original Teenage Mutant Ninja Turtles were really violent and gory comic books

Not only that, they also cussed constantly and got drunk! These were the TMNT in the original 11 issues. Later on the show was geared to entertain children, so they had to tone down the violence, language and drinking.

Additionally, the original storyline was quite different to the movies and cartoons. We strongly recommend you to visit the source and see for yourself. It is quite interesting!

(Source)