I started hearing this about 7 years ago, and it has become a huge pet peeve for me. I work with a lot of educators, and I hear it often in meetings and presentations. In fact, the high school guidance counselor at my son's school said it just last night.

Examples include "on tomorrow," "on yesterday," and "on next week." It's like fingernails down a chalk board to me. grin

P.S. I also hear "on accident" (as in, I did it on accident). Where did THAT come from??