Omigosh, those meat and mayo cakes are just downright cruel! Imagine cutting into a cake and expecting sugar and chocolate and stuff, only to find that...grounds for divorce (or jail time), if you ask me.
As for worst cake disasters, I'm reminded of a 'cake-off' that a few of us had when I was a teen. Basically the guys were bragging that they could bake a cake just as well as any girl, so we (girls) challenged them and they took us up on the dare. Well...about three hours (and a few empty 'bottles of encouragement' that the guys had) later, we walked in to see how it was going. Let's just say this: the cake-off took place in my dad's kitchen while he was at work. The guys claimed that their cake was finished, and when we asked to see it they at first balked, but then relented, only to reveal something that was either a remnant of some UFO (Unidentified Freaky Oven) or...worse yet...something that may have emerged from a person harboring a major cold/sinus infection (no further description needed there). One of the guys offered to 'slice' us a piece, and when he was finally able to remove a part of the gelatinous goo from the pan, he decided to demonstrate just how awesome this cake really was, and he threw it across the room...whereupon it hit the wall right next to the door, and it stuck.
All would have been well except for one thing: Right at that particular moment my dad happened to open the door and walk in, and the projectile cake-mucous missed his head by mere inches. He stood there silently, his face changing into a rather interesting shade of red-purple hues, cake-mucous slowly leeching its way down the wall beside him. If only I'd had a camera to capture the look on my dad's face right then (however, now that I think about it...had I taken a picture I probably wouldn't be here today to tell the story). Cake-off was officially over when all of the guys frantically scrambled to leave, as they simultaneously all recalled pressing appointments they just had to keep.
I'm not sure if anyone actually dared try and taste a slice of the guys' cake, but I suspect it would have been safer than remaining in that kitchen...