unbutton = rozpinać (np. marynarkę)

Hands A Guy Unbutton His Bright Shirt Close Up Stock Photo ...

Source: http://www.123rf.com/photo_34357194_hands-a-guy-unbutton-his-bright-shirt-close-up.html

rozpinać (np. marynarkę)

unbutton = rozpinać (np. marynarkę)

English sentence and Polish translation

Unbutton your shirt, please. = Rozepnij swoją koszulę, proszę.