Exploding Egg (RTDW)

Anna and I made some cookies tonight. I measured out the sugar while she thawed the butter in the microwave and added it to the bowl. Then I got out the eggs, I cracked one and handed her the other. I turned to throw my shells away when I heard hers crack, then silence. I turned back and saw half the shell in her hand. I hurriedly turned off the mixer as she stood there stunned, then she stated: "it was an exploding egg"