Eyes the Size of Saucers...

Today, helping my boys study for exams, I was asked to read out a whole lot of words of masculine type, of which they had to give the feminine..... so I get to this word and I say "Luke... Cock", he looks at me with eyes the size of saucers and says...... "are you serious.......?" Luckily his sister (Aimee 8 years old) comes to his rescue and says "Hen".