Chandler: For us, kissing's an opening act.. like the comedian you have to sit through.. before Pink Floyd comes out

Is comedian being an opening act a thing? Who is Pink Floyd?

The gang is discussing the meaning and importance of kisses before sex. Chandler voices guys' perspective on the matter.

Chandler: For us, kissing's an opening act.. like the comedian you have to sit through.. before Pink Floyd comes out

What is an opening act? Why the comedian is in it? And who are Pink Floyd?

Let's start from the end. Pink Floyd are one of the most commercially successful and influential rock bands of all time. This English rock band was formed in London in 1964. Interestingly the author Jere 

O'Neill Surber once wrote: "their [Pink Floyd's] interests are truth and illusion, life and death, time and space, causality and chance, compassion and indifference." 

Remember it is still only the second episode of Friends in the show, and the characters of six friends are still being stated at every opportunity. Knowing that Chandler is a fan of music/lyrics of such soul-searching kind is paints him in my eyes with some nice complex color. 

The opening act's performance serves to "warm up" the audience for the main show. Such warm up helps making the audience excited for the headliner in Chandler's example it is Pink Floyd. The opening act can be singing, or comedy, or a sketch.

Warm up sessions date back to the time before television even, to radio shows. So it is pretty common in US, to have someone less popular to get new 'cold' audience to the right mood temperature before the star would come out. That the job Chandler and it seems the other two guys assign to kissing. 

But as we know girls have a pretty much opposite opinion!