This 1791 print is entitled "THE LUBBER'S HOLE... alias... the Crack'd JORDAN" because Gilray believed wholeheartedly in CAPITALIZATION. The speech bubble is a nonsensical nautical cry of glee (an articulate "Yar! Yar! Yar!"), because Gillray Had No Freaking Clue how the hell sailors talked.
The subjects of the painting are the actress Dorothea Bland, who went by Mrs. Jordan (Mr. Jordan was what one would call a figure of speech) and was famous for doing cross-dressing comedic roles at the Drury Lane Theatre, and the Duke of Clarence, the third son of George III and a member of the Royal Navy- as can be seen with the blue and gold coat hanging on the wall.
Jordan is unfortunately a slang word for "chamber pot" and Mrs. Jordan was well-known for her vulgarity and the number of men who made her their mistress and later tired of her, hence her representation as a cracked chamber pot on legs. By far the most famous of her... suitors... was the Duke of Clarence, who gave her ten children and dickishly told her she'd get a pension only if she gave up the stage. Mrs. Jordan did so, but was forced to return to the stage when one of her sons-in-law fell greviously into debt. Her pension vanished and she died in poverty in France, as did a number of Regency Celebrities. Fleeing to France in poverty was basically the 18th century equivalent of going into rehab.
The Duke of Clarence later became a king of England (King William IV), but most people thought he was a really crappy sailor, too distracted by impregnating Mrs. Jordan to actually do anything of consequence. The fact that he did not take part in the Napoleonic wars because he had fallen down some stairs drunk and broken his arm, thus rendering himself incapable of command and convincing the Lords of Admiralty that he was Too Dumb To Live, did not do him any favors. Gillray calls attention to this by making the Duke of Clarence go through the lubber's hole; it was a naval tradition to get up to the crow's nest by climbing the diagonal netting up to fifty feet above the deck instead of just climbing up the mast and pulling oneself through a hole (the lubber's hole) to the platform of the crow's nest. Real Men, you see, don't follow safety precautions.
However, by the time he became William IV, everyone was royally pissed off at his elder brother George IV who had massively overspent his income, gone completely mad and horrifed most of British society with his hedonism and his lechery and he was welcomed with open arms. William IV was better recieved as King of England than Duke of Clarence (the Duke of Wellington said that he "he had done more business with King William in ten minutes than he had with George IV in as many days"). Despite his conservative opinions, his reign saw a large number of reform bills, the total abolition of slavery, a weakening of the generally conservative House of Lords, a welfare bill, and the establishment of child welfare laws. This came, of course, with a weakening of monarchal influence.
Since the House of Hanover was known to have porphyria and a genetic history of stupidity, this could be seen as a good thing.