Wiktionary
laugh down
vb. 1 (context transitive English) To cause to cease or desist by laughter. 2 (context transitive English) To cause to be given up on account of ridicule.
Usage examples of "laugh down".
Mr Ibbs has got his wind up, we're having a right old laugh down here.
The female, when her risibility is once aroused, can laugh down the hyena or the jackal or the wild-cat.