When I play Twitch it feels like I'm praying that I don't get blown up instantly so I kill the whole enemy team.
However, the way the ability originally worked was that it did turn Twitch's autoattacks into slow, dodge-able, linear skillshots with the same range and AoE as they currently do. But there were so many situations where the enemy would just sidestep autos to take no damage, making it so Twitch's ult was very rarely worth using and would cause him to lose duels he would win if he hadn't used R at all, so Riot changed it to make the ability feel better.
Later, Riot changed the ability's name to "Rat-ta-tat-tat" to reflect the altered functionality, but the name simply didn't stick with players. Everyone still called it "Spray and Pray," even casters in pro games, so Riot reverted the name back to "Spray and Pray."
It's kinda similar to the name for Lux's ult which was originally named "Finales Funkein," then "Infinite Light," and finally "Final Spark." Players generally called it "Master Spark" (or just "Laser") the whole time and were not going to bother remembering a German phrase.