There once was a time when people didn't bond through their love of complaining. Instead, friendships were forged out of mutual interests and complementary personalities. Although that is still the case today, there is an ever-growing culture of self-hatred and jaded cynicism which has pervaded social interactions between teenagers.
This is incredibly unhealthy. Flippant jokes about one's personal sufferings can be a way to unite people under shared struggles. It is relieving to find out that one is not alone, and several people share your trials and insecurities. It is cathartic to revel in your shared misery, especially in a culture which promotes absolute perfection. However, there is a line between finding community through shared struggle, and creating a community which fosters misery for misery's sake.
It's not bad to openly say you like how you look (even if you aren't considered typically beautiful by society at large) or that you consider yourself talented. It's not self centered to deflect compliments or be assertive.
Some people consider casual self hatred as a coping mechanism, but ultimately this will only excacerbate the issue. Saying you hate yourself out loud won't make you love yourself. Externalizing every negative emotion you have is just as bad as internalizing every negative emotion.
If you find yourself making several suicide jokes a day or frequently openly criticizing your weight, it's time for you to consider why you find it easier to make light of your insecurities instead of actually fixing them. Learn to respect yourself. Learn to acknowledge your struggles and tackle them instead of immersing yourself within them.
It isn't normal to hate yourself, no matter how encouraged it is. Find the strength within yourself to grow.