[2rooi123]

denon c560

 

[Pott]

For four different budgets:
CX500s
S4s
Super Fi. 5s v2
IE7s
 
I have all four and they all sound fun and pleasant to my ears. They just make the music easy to listen to and enjoyable, not for critical listening (which I have no interest in).

 

[mvw2]

Fun generally means colored, although I will say it doesn't have to.  Part of the idea of fun is to also have the earphone engaging and in some cases aggressive.  You want something that catches your attention and hangs on to it.  There should be something special to in in terms of how it presents the music, something unique, maybe a wow factor.  Sometimes an earphone can be too analytical, sometimes too revealing.  Fun can potentially take aside to analysis and processing a lot of new information.  In the end, you just want something that will get your toe tapping.
 
For me, one of the more fun IEMs out there is the Triple.Fi 10.  It's aggressive and enveloping.  The presentation is a lot like that of being in a club and just surrounded by sound.  It's detailed and accurate but also powerful and engaging.  It's hard not to enjoy this earphone.  Even when EQed flat, it's just as good because the sound is thick (for a BA driver earphone) and robust.
 
Another great mentionable is the Fischer Eterna, at least v1.  It's presentation is much like that of a good car audio system with a nice sub.  You get good mids and highs and a dominant bass line that drives the whole experience.  It's a very likable earphone, and the response is a lot like the Triple.Fi 10 but short the treble emphasis. 
 
Someone mentioned the V-Moda Vibe.  Yes, these are very fun earphones.  They are warm, thick, and velvety.  The sound is big and enveloping.  They lack the SQ of higher end options, but they are some of the funnest earphones I've used.  I currently feel there are better options out there though, but the Vibe has a unique presentation that really isn't common among a lot of other earphones.

 

[mark2410]

well it depends greatly on mf mood what i find fun but if you asking what V shaped sounding things i enjoy id say
 
C751, TF10 and IE8

 

[SolidSnake3]

Right now I would have to say the Coppers although straight from an ipod I don't really get that feeling. When running them from my Little Dot II though, I really do get that rock out sort of vibe. Have a pair of Eterna v1's coming in a week or so, that may unseat the Coppers in the fun regard

 

[G3n0c|d3]

i would say eterna (the first edition) got my vote for fun sounding... i just jacked it on my iphone, volumes up a bit and ready for my air guitaring when listening to my fav metal songs...

 

[onyohasa]

SM3 with the right tips.