(Warning: This post may contain spoilers.)
Great Teacher Onizuka is a totally ridiculous yet lovable anime about a 22-year old, crazy, over-the-top, good-for-nothing, ex-gang leader named Eikichi Onizuka whose dream in life is to become a high school teacher just so he can get close to all those high school girls. After several failed attempts at passing the exam to qualify as a teacher and even more disastrous attempts at getting hired, he gets a lucky break when a school principal notices his passion for never belittling students (since he was always belittled by his teachers when he was in school). Unfortunately, he gets assigned as the class adviser to the most notoriously problematic middle school class ever, and to his dismay doesn't even get to see any high school girls at all.
But between Eikichi Onizuka's idiotic antics and highly unconventional teaching methods, his students are gradually learning not only from textbooks but also from life itself. As I was watching the 43-episode series, I found myself wishing I had had a teacher like Onizuka when I was in high school. Because... while Eikichi Onizuka may not fit the description of a "good role model" or even a "good teacher" for that matter, what with his bad habits and all (e.g. smoking, being a ladies man, breaking the law, etc.), the life lessons he teaches his students impacts their lives in a big, positive way. And when all is said and done at the end of the day, his students are better off having known him.
This is an anime that I would definitely recommend watching. Who knows, you might even learn a few things from the Great Teacher Onizuka. :)
Added bonus:
The opening and ending themes are very catchy tunes that you can listen to all day and sing in the shower.