It's a CONVERSATION starter.
The Big Bang Theory Season 3, Episode 11
...to provide Amy with CONVERSATION
and casual physical contact.
The Big Bang Theory Season 6, Episode 1
...to introduce
an alternate topic of CONVERSATION.
The Big Bang Theory Season 4, Episode 7
into a CONVERSATION for years.
The Big Bang Theory Season 12, Episode 3
...but tread carefully because it may be
the last CONVERSATION we ever have.
The Big Bang Theory Season 3, Episode 5