Board Thread:General Discussion/@comment-27907368-20160412010659/@comment-26242189-20160420003309

Alphys knows about Alternate Universes:

http://vignette2.wikia.nocookie.net/pbesantivirusisterrible/images/e/e0/Yougotthatright.JPG/revision/latest?cb=20160409005714

She says this if you choose "Unknown" as Alphy's crush in the Mettaton Game Show.