The character in this episode of Extras is pretending that he has plenty of money and can pay for his friend's dress. However, he still tries to get a discount but it turns out to be such a small amount that he says to the saleswoman, don't bother taking the £25 off the price, in fact you might as well stick it on… that is, add it to the price. So he is trying to get a discount while at the same time pretending that he doesn't care about the money.
not a teacher
Interested in Language