The weirdest I've heard of was from Russia. Many years ago one new friend wrote a six digit for another, who forgot it in their pocket. Much later that person found the number, and thought of their acquaintance and dialed it:
-Ivanushka?
-Yes?
-It's Maria, we met in Tver in the 70s. . .
-I remember, but how on earth did you now where to find me?
-You wrote your number for me
-No I didn't. I didn't live here, then.
-But I just found it in my pocket!
-No, what I wrote then was the DATE!