Note to King Lear, 1.4.225

King Lear,
Act 1, Scene 4, line 225
Whoop, Jug! I love thee: —This may be a snatch from a song. "Jug" is a nickname for "Joan," which is a typical name for a female servant, and perhaps for a prostitute. The Fool, in his false-random way, is aiming another barb at Goneril, who is probably still frowning and expecting to be taken very seriously.