Know Your Partner
This game works well if played by a group of couples. The group should take turns to question each member of the party about how well they know their partner. The partner of the person being questioned should leave the room while this happens. You could compile a set list of questions for each couple to answer about each other or tailor your interrogation to suit each individual. You could start by asking what day they were married or what their partner was wearing on the day they met. Partners score against each other and are awarded a point for every question they get right. The couple scoring the highest number of combined points are the overall winners.
Strip Poker
Perhaps best suited to a younger group of adults, in this game, the participants play a standard round of poker or any other card game of their choice. Instead of playing for money, the person with the worst hand in each round has to remove an item of clothing. It's best to agree just how far your group deems it appropriate to go before you start. Add a twist to the game by drawing up a series of forfeits that losers can choose to do if they don't want to remove an item of clothing. Try to make these as embarrassing as possible so that the loser will be forced to think twice about accepting the forfeit.
Classic Board Games and General Knowledge
Most adults enjoy demonstrating the breadth of their general knowledge and intelligence at a dinner party. Once this has been done to everybody's satisfaction in conversation over dinner, games like Trivial Pursuit or Articulate offer a good way for members of your gathering to flex their intellectual muscles. You can also find adult versions of games like Pictionary and Balderdash that would be well suited to a more mature crowd. You could even consider compiling your own general knowledge questions and delivering them in the form of a pub quiz. Mix the couples up into teams of two and have a good bottle of wine ready as a prize for the winners.
Name That Tune
Connect an MP3 player or a computer with a music library to an amplifier and set it to shuffle songs. The fastest member to identify each song receives a point. Keep a tally throughout the course of the game to see who identifies the most in the shortest possible time. You can carry on with the conversation once each song has been correctly identified.