The first option, "Laying on couches is boring", is correct. The word "laying" is used as a gerund here, meaning that although "lay" is a verb, "laying" is a noun. This is a singular noun, so saying "laying is boring" is just like saying "The book is boring" or "My cat is boring".

"On couches" is a prepositional phrase, modifying the gerund, so basically it's an adjective. It's like saying "The green book is boring", or "The book about fish is boring". In both cases, "green" and "about fish" are used as adjectives, and don't really directly affect the verb.

So it's "laying on couches is boring" because "laying" is singular, and you would still use "is" even if there was only one couch ("laying on the couch is boring"), as "on couches" only describes the noun/gerund.

The first option, "Lying on couches is boring", is correct. The word "lying" is used as a gerund here, meaning that although "lie" is a verb, "lying" is a noun. This is a singular noun, so saying "lying is boring" is just like saying "The book is boring" or "My cat is boring".

"On couches" is a prepositional phrase, modifying the gerund, so basically it's an adjective. It's like saying "The green book is boring", or "The book about fish is boring". In both cases, "green" and "about fish" are used as adjectives, and don't really directly affect the verb.

So it's "lying on couches is boring" because "lying" is singular, and you would still use "is" even if there was only one couch ("lying on the couch is boring"), as "on couches" only describes the noun/gerund.