This game is quite simple. Let's say the first poster Says:

poster1
Sorry I ate your mum


The next poster would say something back for their first line, and then the second line is their little 'sorry I...' sentence.

Like this:
poster2
No worries my Cannibalistic friend, she always nagged me anyway!

Sorry I called your house at 5am hoping you were awake and in the mood for LOVE~


With that (Sorry if unclear~) I say:

Sorry I om nom nom'd the s**t outta your head~