Possible Clues:

• Slough, bog
• If you get stuck in this, more fool you, by the sound of it
• Slough - marsh
• What a sillier-sounding bog!
• It might sound sillier to get stuck in it
• One might stick there or during the Mass
• More fool you if get stuck in it!
• Is the artist in the middle of the wet plants? More fool he, by the sound of it
• Soldiers restricted by service in the mess
• Swampy area