I'm reading "Hatching Twitter: A True Story of Money, Power, Friendship, and Betrayal" by "Nick Bilton"
At some point, CEO was fired and all employees are sad and confused. The author had used this paragraph to describes the situation:
But the mood wasn’t jovial. There was no laughing. There was only tension that could have been sliced with a tweet and sadness, even among the winning team.
What does the second sentence mean?