Egg in a hole is a traditional Nordic breakfast, it was first made by the Viking tribe Na-Hee-Wae. It's a peice of bread with the centre cut out and the egg is fried in the middle. The Vikings preffered this breakfast due to the ease of eating it. They were able to eat it just like toast or a sandwhich and get enough protien and energy to carry them through battle.
Thor: Must prepare for battle, toast no good.
Bob: Why not have egg in a hole!
Thor: Good idea! I'll put bacon between 2 of them!