The heroes (or the villains) need access to a McGuffin, which is usually heavily guarded. Just getting in will be a shore. But what if you can get invited in? Welcome to the Black-Tie Infiltration, where you can simply waltz through the front door in your best attire. Now the tropes page gives some good reasons why the protagonist might chose this route into the villains lair, but the truth is that it is an excuse to put them in some eye catching clothing and maybe set the stage for some flirting. The added tension from the social situation (a faux pas can attract too much attention, although a well timed accident can work wonders.
This trope can get the characters in the door, but rarely does it deliver the McGuffin into their hands. That is were a combination of distractions, technology, witty banter, and a few punches (or silenced shots) will carry them to their goal. Getting out can be as easy as calling it an night or as difficult as fighting your way through an army of thugs. Either way, the protagonist will look good doing it, and may even swipe a bottle of expensive champagne on their way out.