This is an irregular verb. It is a model verb.
PresentPresente
Sus bromas avergüenzan a su hermana.
His jokes embarrass his sister.
ImperfectPretérito imperfecto
Aquel apodo avergonzaba a mi primo.
That nickname used to embarrass my cousin.
Negative ImperativeImperativo negativo
Por favor, no avergüences a tu amigo delante de todos.
Please don't embarrass your friend in front of everyone.