MadLipz is an app that lets you dub your own voice onto your favorite viral video clips which is actually pretty funny. FYI it works a lot like Dubsmash, but on MadLipz you're looking at longer videos that tend to last up to 15 seconds and you also get the chance to record up to three separate audio tracks.
With several different tracks to add to each clip, creating whole conversations and more complex original compositions is totally an option here. Each track is saved independently, so editing them separately to get each track in tip-top shape is easy enough to do. Basically, in terms of originality, the sky is the limit.
The nice thing about MadLipz is that it has a complete database full of colossal video clips some of which are easily the best the internet has to offer. That way you'll have literally thousands of hilarious clips from 5 to 15 seconds long at your fingertips, allowing you to record your own voice onto them. Plus all these clips are perfectly organized into well-defined, easy to navigate categories.
Once you're done dubbing your voice track -- all you need to do is pick which social media site you want to load it onto. Alternatively, of course you could always just save it on your phone's memory for your own private amusement.
If that doesn't seem like enough, any MadLipz user can upload their own clips to the app's database. Be forewarned, though as that's going to mean a bit of typing on your part. In order to upload your own videos, you'll need to add a proper title and tag your video appropriately so others can search for it and find it easily.