Guest Royals and installing Joywires.

[lawfuldread]

Joywires are illegal on many worlds, and are known for destroying whole cultures.

So, at the cost of 20 steel and 4 components, you can give your guest a noble 30 happiness. Pffff I don't need to give them a proper room or even a throne room just fork over 4 components and own a skilled doctor to satisfy them.

Exploit and should be reported or within flavor for nobles would probably install these.

[Hatti]

But you can install a mindscrew too if they are too happy for you!

[lawfuldread]

You joywire them while they visit, then you have 4 days to remove it, install a mindscrew and send them on their way.

[Alenerel]

You joywire them while they visit, then you have 4 days to remove it, install a mindscrew and send them on their way.

Next quest the same noble comes along and instantly goes berserk.

[DuckBoy]

I'd be worried about uninstalling the joywire. 

In my experience certain surgeries tend to make the royals unhappy with your colony.  Including:
Downgrade psychic amplifier
Remove lung
Remove kidney
Remove heart