Go and boil your head
An insult, of the form go and do something bad for yourself. Other examples are, go and play in the traffic and the more recent, and vehement, eat shit and die.
This could be related to the fact that in South Pacific societies cooked food was 'noa' or the opposite of tapu (tapu is loosely translated as 'sacred', although it has a deeper meaning than that). The head was considered the most sacred part of the body and one doesn't usually pat children on the head, or stroke a person's hair. An exhortation to turn your head into cooked food was regarded as the greatest possible insult.
The earliest citations of the phrase in print in English don't exactly support that derivation. The original meaning of the phrase was rather milder than it is now and relate to people who were told to stop promoting silly opinions, that is, don't be so stupid. These example date from the 1930s. In the UK there's a version of it in Compton MacKenzie's satire on the British intelligence services, Water on the Brain, 1933:
"Go away and boil yourself"
In the USA, an edition of the San Mateo Times from May 1935 included:
"And now as to your other proposition, it's out before it's in. Go climb a tree. Go boil your head."