VLADIMIR
You're a hard man to get on with, Gogo.
ESTRAGON
It'd be better if we parted.
VLADIMIR
You always say that and you always come crawling back.
ESTRAGON
The best thing would be to kill me, like the other.
VLADIMIR
What other? (Pause.) What other?
ESTRAGON
Like billions of others. (2.85-90)
Whoa there. Like billions of others? We’re thinking this isn’t literal. First, let’s go back to that line in Act 1 when Pozzo says that it would be better to kill Lucky than to send him away. Estragon is definitely repeating what he’s heard, even as he denies remembering anything about Lucky and Pozzo from the day before (this denial is what prompts Vladimir to declare he’s a difficult man to get along with). It would seem then that Estragon is either mindlessly repeating things, intelligent-parrot-style, or he agrees with the claim that death is better than isolation. As to the comment about others, Estragon is simply equating his and Vladimir’s relationship with all the other "billions" of relationships in the world. The thought that death is better than loneliness, then, applies to everyone, not just these crazy guys on the stage.
VLADIMIR
We could play at Pozzo and Lucky.
ESTRAGON
Never heard of it.
VLADIMIR
I'll do Lucky, you do Pozzo. (He imitates Lucky sagging under the weight of his baggage. Estragon looks at him with stupefaction.) Go on.
ESTRAGON
What am I to do?
VLADIMIR
Curse me!
ESTRAGON
(after reflection) Naughty!
VLADIMIR
Stronger!
ESTRAGON
Gonococcus! Spirochete!
Vladimir sways back and forth, doubled in two.
VLADIMIR
Tell me to think.
ESTRAGON
What?
VLADIMIR
Say, Think, pig!
ESTRAGON
Think, pig!
Silence. (2.359-370)
Because they don’t know how to have a real relationship themselves, the best Vladimir and Estragon can do is imitate what they see around them. The tragedy is that they are imitating an abusive and unhealthy relationship, as it’s the only example they have.
VLADIMIR
Moron!
ESTRAGON
That's the idea, let's abuse each other.
They turn, move apart, turn again and face each other.
VLADIMIR
Moron!
ESTRAGON
Vermin!
VLADIMIR
Abortion!
ESTRAGON
Morpion!
VLADIMIR
Sewer-rat!
ESTRAGON
Curate!
VLADIMIR
Cretin!
ESTRAGON
(with finality) Crritic!
VLADIMIR
Oh!
He wilts, vanquished, and turns away.
ESTRAGON
Now let's make it up. (2.413-24)
It’s as if Estragon and Vladimir use each other only to pass the time; each man is only seen as entertainment, not as another real, genuine human being.