I know that your one meme just got to 1000 upvotes, but ignore it for now and pretend you're offline. You don't have to keep your promise, and even if the community hates you for it, that's temporary. Having a picture of your face online leaves a permanent footprint, and with some of the technology we have today, it's possible to predict what you'll look like decades in the future. So you can have a bunch of kids/ teenagers be mad at your online character for a little, or you can permanently forfeit your online safety. It's your choice.
Just stay offline for a little bit, wait for them to forget, and problem solved. If you want, you could even apologize. Besides, they're probably madder at me for spamming than they will be at you. Also, it's not worth stressing over. Just ignore IMGflip for a while or use a different account, and don't worry about it. They can't force you to do anything.