In your mother's eyes
It means that something looks bad. Or if you wear something that's totally ugly and your mom thinks you look "handsome" or "pretty".
"Hey, guys does my outfit look good?"
"Only in your mother's eyes."
"Oh my god, I just drew the best Shrek!"
"Pfft, only in your mother's eyes."
"Only in your mother's eyes."
"Oh my god, I just drew the best Shrek!"
"Pfft, only in your mother's eyes."