A pressed skull, eh?

But pressed onto what?

Maybe a skull that was pressed onto paper would work.

Or pressed onto a flag.

Where have you seen a skull-and-crossbones flag?

You need the Jolly Roger.

Where are these flags usually flown?

A Jolly Roger flies above the crow's nest.

You can reach the crow's nest by climbing the rope ladder in front of the mast on the main deck.

Now just take the Jolly Roger, and add it to your Monkey Island Mix.