Pooh-pooh

[W]hen he went abroad with Dombey and was chasing that vagabond up and down France, J. Bagstock would have pooh-pooh'd you—would have pooh-pooh'd you, Sir, by the Lord!

Source: wiktionary

In England, until very late days, we have been accustomed rather to pooh-pooh national Orders, to vote ribbons and crosses tinsel gewgaws, foolish foreign ornaments, and so forth.

Source: wiktionary

Mr Macey, though he joined in the defence of Marner against all suspicions of deceit, also pooh-poohed the tinder-box; indeed, repudiated it as a rather impious suggestion, tending to imply that everything must be done by human hands, and that there was no power which could make away with the guineas without moving the bricks.

Source: wiktionary

Pooh-poohing the IPCC's science has been one line of attack by [George W.] Bush's backers.

Source: wiktionary