That was the intention of the Serious part 
Glad it stuck! 
I know this is a closed poll (I just spotted it)
FYI: There is a Serious Engine (Serious Sam I and II were based on it I believe).
http://www.croteam.com/engine_overview.shtml
I know that this is just the slogan, but I wanted to mention it just in case there are any issues…
Woo hoo! Bring back "Monkey See" to avoid trademark infringement issues!
I kinda like: Get Down With A Funky Monkey
Whatever happened to the oh mighty slogan anyways? Can't say I've really noticed it ^^
I'm good with slogans, can we have a new poll? ;D