CockTail Dinner~~ What to Wear??!

uh-huh! from my previous few post...i mentioned my bosses coming right?
confirmed coming next week ard 05 Aug oo.... 1 Director 1 Senior Manager & 1 Lady from Marketing operation department. hehe~

Hmm, we invited some of the travel agency's bosses or manager to a Cocktail Dinner @ Hilton, currently set venue@ Senso....yo! Let's Party again!!!!
When I am the doing the invitation thru phone calls to those Agents....they start asking like "oh! ur product launching isit? " "workshop again isit?" "oh! Seminar kah?" hahaha...its not workshop or prodcut briefing like we've done b4...this time is actually a Informal Gathering...

already said It's a COCKTAIL DINNER wad....and yet @ senso.. so ofcos is to "DRINK!" and mingle around to chit chat and to "pei yang gan ching" mah~~ haha!

NOW!! the Question is...who d hell can tell me...WAD SHOULD I WEAR???????????!!!!!