You're new, so I'll be nice... Reposting is considered a REALLY bad thing among memers. If it seems flash-of-brilliance-clever, try looking for it in Google Images (or whatever search engine you prefer) to see if it's been done before.
Being nice because they are new, as opposed to putting a reposter on blast and watching them get trolled by the Imgflip community.
It's a "Do unto others" sort of thing. You wouldn't want someone else taking credit for your clever and original memes, so if you're going to repost (which is even mentioned in the rules when you submit a meme), at least say so.
But, whatever, do what you want... Don't whine if you repost and everyone trolls you about it.