Funny communities and news ones are usually found in generalist instances such as lemmy.world or lemmy.ml but the most interesting ones are on specialised instances.

The best way to discover them is to go directly to the instance and scroll a bit on the local thread or to go to the community page (ex: lemmy.ml/communities).
Then come back to your instance to visit again or follow the communities you liked.

There is geographically or language specialised instances such as :

• feddit.uk
• feddit.it and most probably
• feddit.[your country code]

but a few geographically/language specialised instances were creative with there name such as

• aussie.zone
• jlai.lu
• midwest.social

There is also subject oriented instances for example

• mander.xyz. Science oriented
• slrpnk.net. Solarpunk oriented
• lemmy.dbzer0.com. Allow content about piracy

and !piracy@lemmy.dbzer0.com is probably the most follow community on the lemmyverse.

You can find community directly from your instance page or from a browser like :

• browse.feddit.de
• lemmyverse.net

The browser helps you find community's names that were never connected to your own instance or specialised instance you didn't knew about.
When connecting for the first time type the url lemmy.world/c/[community's name]@[community's instance], you'll get an error but after refreshing the page you will have access to the community. But that's not new-comers friendly as you'll need another maneuvers to access post published before you connect your instance to the remote community. Still, if you are interested, I can explain you how to do it.

There is also politically oriented instances but some may be blocked by the administrators of your instance. You can check that on lemmy.world/instances.

Finally, if you want to test your options on Lemmy without spamming your favorite communities, you can do that here !testfediverse@jlai.lu.