The trouble, it seems, was with the third-party keyboard's cloud sync service. Users were somehow receiving data from other user's SwiftKey language models -- providing them with text entry predictions intended for someone else entirely. On a surface level, the glitch sounds harmless enough, but commonly used contact information can wind up in your Swiftkey database. Users on Reddit reported finding email addresses they weren't familiar with offered to them on login pages, and some users even received phone calls from folks who found their number through SwiftKey's predictive text. That's a really weird way to have your contact information leaked.
SwiftKey says that the issue only affected a small number of its customers, and has temporarily disabled its cloud sync service and removed email address predictions from its apps. The company asks users who think they may still be experiencing the problem to contact them at email@example.com. As for the rest of us? We'll probably text a little more cautiously. Autocorrect errors may be a meme, but not everybody wants to be a part of the joke.