Vine
They had started out simple, attempting to create a username that people would remember. Having decided that they weren't going to use their names, the twins had spent hours pouring over their ideas, trying to formulate a username that anyone would be proud of.
It was between 'gredandfeorge' and 'marauders2.0'. They couldn't decide which one would fulfill their destinies a bit better. Where 'gredandfeorge' had a homely feel, the latter was new, different, and would certainly confuse people that didn't understand.
There was no doubt which one they utilized.
However, there was yet another predicament. Which picture, if any? Which name? What should they even try to vine first?
A selfie was carefully taken, with no filter added, of course. Their names were typical- Gred and Feorge - and it was with a grin that Fred produced from his pocket a few Canary Creams.
"We can't use that, mate. Muggles would think we're..."
Fred arched a brow, but argued for it anyway. They wouldn't know, because they didn't know magic. To them, it would have something to do with elek-tricty.
"... up to something."
In the end, they went with the Canary Creams. George filmed, holding the button with furrowed brows, while his brother rapidly stuffed the sweet in his mouth, winking at the camera as he morphed into the bird. The fiercely yellow creature squawked, but when the filming teen looked down at the time, they still had a few seconds left.
He paused, waited the few minutes for Fred to slowly turn back, and pressed play just as he was molting his feathers.
They repeated the process a few times, attempting to make it flawless. Once the six seconds looked like they were all in a stream of moments, it was posted, with only two tags: 'birds' and 'illusions'.
It took approximately four hours before they officially hit one thousand followers (obviously, they didn't understand how amazing it was until they receive an angry owl from Dean, who has barely one hundred). The next day, they chose to post something similar, this time eating one of the Ton-Tongue Toffee pieces that they had recreated.
That, too, was a massive hit, as George was wiggling around his long tongue, Fred tugging on it, and Ron attempting to hold the phone straight.
There other vines also consisted of Weasley Wizard Wheezes products, though some were simple charms and pranks. Their slap-cam was hilarious; they attempted to do it on their mother, who instantly hexed Fred into a frog.
They kept this a secret for quite some time, not trusting their mother to let them keep it. After all, she was barely able to purchase phones for the lot of them. She'd consider it a breach of the wizarding world, tell Dumbledore, and make them delete their now insanely-popular account.
Molly does find out when the twins are out for the day. Fred had forgotten his phone, and the first thing she saw upon opening it was 'Vine'. She was extremely curious, as well as concerned.
All of their phones, after all, were old flip phones.