"When you have sex in the front bedroom at 2:30am, I can hear your bed thud and your girlfriend moan. Please to stop."
"Would it be possible to move your bed away from the wall and to check the bedposts to see if they're properly screwed in?"
"Are you really having sex faster than a jabber beatloop? Because I don't know whether to be envious or appalled."
It's rather delicate.
UPDATE. Rilkefan bestowed this solution in comments, and it's too wonderful to be hidden under a click:
I know that your girlfriend's a moaner,
A fact I did not seek to know.
Tomorrow at three I may phone her,
And tell her it can be nice slow.
I fear that if we have an earthquake
Some morning about half past two,
Your ill-fastened bedposts will buckle,
And the adjacent wall will crush you.
I wish you less aerobic coupling.
I wish you conubial bliss.
I wish you could use the back bedroom
And act like you never read this.