Top 10 Weird ICD-10 Codes

Burn Due to Water Skis on Fire (V91.07X)

Impressive and worthy of its own code.
Other Contact With Pig (W55.49X)

What contact you ask? Well, it's got to be something other than bitten (W55.41X) or struck (W55.42X). Those have codes of their own.
Problems in Relationship With In-Laws (Z63.1)

This is a code that's probably worth remembering.
Sucked Into Jet Engine (V97.33X)

You never know when this code will come in handy, plane and simple.
Fall On Board Merchant Ship (V93.30X)

Not to be confused with falling on cruise ship due to (alcohol use, unspecified with intoxication, uncomplicated [F10.920]).
Unspecified Place in Prison as the Place of Occurrence of the External Cause (Y92.149)

Injuries occurring in the kitchen, dining room, bathroom, cell, swimming pool (?), and courtyard all have their own codes.
Opera House as the Place of Occurrence of the External Cause (Y92.253)

Follow-up question: Was a phantom involved?
Prolonged Stay in Weightless Environment (X52.XXX)

Because astronauts are patients too.
Struck By Turkey (W61.42XA)

Use of this code usually goes up around Thanksgiving time. If a duck acts as an accomplice, there's a code for that too (W61.62X).
Bizarre personal appearance (R46.1)

In case you're feeling particularly judgey, there's a code for that.