Leading Light 

Rhyming slang for "Gobshite". People who explain quite confidently how things should be done, but really they have no clue, or their own agenda that benefits no-one but themselves.

He's explaining how war benefits mankind, what an utter Leading Light.

Leading Light by RealityIsASimulation August 16, 2022

leaving the porch light on 

When a swinger couple, or an otherwise cheating spouse puts out a subtle hint that their significant other isn't home and they are available to cheat.

Often used to let another cheating spouse know the coast is clear to sneak in a house and start bumping uglies for a quickie

Karen wanted to let Dan know she was ready for some dirty cheating sex so started leaving the porch light on when her husband was gone for work

leaving the porch light on by Rick2024 June 11, 2023