Gosh! Vikings gave each other riddles. Imagine getting a piece of wood with carved runes and once you found the answer you read: "Kiss me". Precious little Vikings. Oh my. 
True story! Norse Rune code cracked - Medievalists.net
Surely a thing I will add to my personal IrelandxWales headcanon. Giving each other riddles to communicate. Ahhh.... I love the thought.
