I often forget these guys, but holy damn how hilarious they can be...
First impression is silly children's show, but give it a chance, I find it absolutely hysterical at times
In Norway they were widely known from childrens TV in the 80s, as "Two good neighbors"
Czechoslovak animation, based in Bratislava (Slovakia), although I see plenty of Czechs taking credit for it - I'll let Czechs and Slovaks fight this one out, and not get myself involved :V
If you want to youtube for more, beware of two things though:
1. Joke voice-overs, they seem very popular, but are obviously made by fans or jokesters
2. The most recent seasons, as they do indeed seem to be aimed more at children (the old classic episodes sometimes even had an adult-theme warning in some openings)