Joke about the Soviet plane TU-154-2-B

Passengers in the plane ask the stewardess:
-Why our plane is called TU-154-2-B?

Stewardess:
-the commander of the plane has explained to us:

"TU" - Tupolev is a Russian aerospace company
"154" - Quantity of passengers
and "2-B" is I and Natasha (The letter B - the first letter of word B... )