To end the argument: Eggs are considered one "cell" but it all depends. The yolk of the egg is ovum (the yolk is the actual cell, the white is just there for energy). The egg is fertilized inside the chicken before the white and the shell are added. In that EXACT moment it is considered one cell but by the time the whites have been added (and the shell) and the eggs is layed, the egg has already divided into millions of cells.
Yes the egg is one cell. No it isn't one cell.