VIPs are special dancers that sometimes appear in the World Dance Floor. You'll know there is a VIP when it says a VIP is "playing" on the left side of the World Dance Floor Menu. The VIP is pretty much just a pre-recorded video of a celebrity or Just Dance employee dancing in the top right of the screen. This only appears during certain songs, so obviously the only songs that count are ones where you can see them dancing. If it says there's a VIP in the World Dance Floor, but there's no video playing, just wait a bit. Generally, their routines show up every 3-4 songs. Throw down some moves when you see the VIP 10 times to grab this achievement. This'll take a few hours simply because of the song rotation, but you can just idle in the World Dance Floor until the VIP shows up again. It will definitely count the same song multiple times, so don't worry about that.
This is what it looks like on the World Dance Floor screen when a VIP will appear:
As you can see, the VIP "playing" is shown on the left side.
If the left side is blank, there is no VIP on the dance floor, and you cannot obtain this achievement because the VIP videos will not appear.Here is a video of a VIP on the World Dance Floor.
Doing this also nets you
List of VIPs that have appeared:Aurelie - Currently OfflineGet Low
Birthday
Jessie J and Tyler Oakley - Currently appearing in XBOX 360, but not on XBOX OneBang Bang
Jan. 8, 2015 Update: Aurelie doesn't appear in the Word Dance floor anymore. The new VIPs are Jessie J and Tyler Oakley, but seem to only appear in the XBOX 360 version, not the XBOX One.