Howard and Bernadette are seen here during a scene fromThe Big Bang Theory. The photo is courtesy of the episode "The Herb Garden Germination."
Added:
Sheldon and Amy are all about spreading gossip in this photo. It's from the episode "The Herb Garden Germination."
Added:

The Big Bang Theory Season 4 Episode 20 Quotes

Amy: The meme has reached full penetration.
Sheldon: Pun intended?
Amy: No. Happy accident.

Amy: I should let you know that she asked for details about our dalliance.
Sheldon: Interesting. So it went beyond the mere fact of coitus to a "blow by blow" as it were.
Amy: Pun intended?
Sheldon: I'm sorry. What pun?