Not much...

Your mother suffers from such an extreme case of alopecia areata, that one can literally see what is on her mind.

She doesn't get the jokes, either.

Your mother's intellectual capacity is of such a limited quantity, that she requires more than two hours to watch an episode of the television program, 60 Minutes.

I also heard her family tree did not fork...

Your mothers frame is ample enough that she is a member of both sides of her family.

Magical Candy

Your mother, who is known over the lands as one who does not step lightly, inadvertently invented the common snack treat referred to as "Skittles" by placing her full weight upon a rainbow.

The proper word is "hydrophobic"

Your mother's countenance is so appalling that when she attempted to bathe, the water abandoned the vessel!

Henny Youngman got picked on in school

Your mother's daily combined caloric intake is of such a long-term imbalance that it has produced in her a state in which, during the act of relaxing about her place of residence, her physical volume fully encompasses said domicile.

Such Large Proportions.

Your mother is of such large proportions, it leads me to recall the time

she first fell in love and damaged it beyond repair.