’”Slug Club”,’ repeated Ron with a sneer worthy of Malfoy. ‘It’s pathetic. Well, I hope you enjoy your party. Why don’t you try getting off with McLaggen, then Slughorn can make you King and Queen Slug —’
'We're allowed to bring guests,' said Hermione, who for some reason had turned a bright, boiling scarlet, 'and I was going to ask you to come, but if you think it’s that stupid then I won’t bother!’
Harry suddenly wished the pod had flown a little farther, so that he need not have been sitting here with the pair of them. Unnoticed by either, he seized the bowl that contained the pod and began to try and open it by the noisiest and most energetic means he could think of; unfortunately, he could still hear every word of their conversation.
'You were going to ask me?' asked Ron, in a completely different voice.
'Yes,' said Hermione angrily. 'But obviously if you'd rather I got off with McLaggen …’
There was a pause while Harry continued to pound the resilient pod with a trowel.
'No, I wouldn't,' said Ron, in a very quiet voice.
—Harry Potter and the Half-Blood Prince, Ch. 14: Felix Felicis