As silly as Murri is being, I too think it's a bit rich to think that a 6 year old couldn't read some words.
My 5 year old can read some sentences, but when she was younger she recognized some other words like the days of the week.
Given this was part of her routine (apparently), I think it is more likely that she would recognize the words on her own underpants - especially the only one that starts with a 'W'.
I am not disagreeing with you whatsoever wonder, just going by what her Mom says. My grandson is 5, has a learning disability and even he can read his name. Days of the week, or letter recognition of all letters isn't there yet, unfortunately. But, why would Patsy have bothered to say that if it were not true? Just wondering about that. It's nonsensical, don't you think?