What anime series can you recommend? Especially, funny ones.

Danshi Koukousei No Nichijou is a riot, and seconding everyone who said Detroit Metal City. And of course the English dub of Ghost Stories is a classic (although some of the references/jokes might be a little dated by now).

Warau Salesman (Laughing Salesman) is VERY underrated! Its basically about a salesman who seeks to "enhance" the lives of people who are going through misfortune in some way, and it shows them failing their end of the bargain and suffering the consequences. Like one episode showed a lady getting a mustache to boost his self confidence as a taxi driver, but then he proceeds to abuse the hell out of it and ends up slowly turning into a Waluigi-