George lies to the boss because if he realizes that Lennie’s mental deficiency is a threat they won’t get the job.
George lies and tells the boss that Lennie is his cousin, and that they left the job in Weed because it was done. George tells the boss that Lennie is not smart, but does not tell him he’s mentally challenged.
When the men arrive at the ranch, they are already in trouble because they were late. The boss is not happy about it. He asks them questions, but only George answers them. The boss begins to get suspicious.
George broke in loudly, "Oh! I ain't saying he's bright. He ain't. But I say he's a God damn good worker. He can put up a four hundred pound bale." (ch 2)
The boos thinks that Gerge might be taking Lennie’s pay because he is talking for Lennie. He assumes that since George seems to be in control, he is taking advantage of Lennie.
George has to be careful, because if he annoys the boss they might not get the job. He needs to walk the fine line of protecting Lennie and not making it seem like he needs protection. If Lennie is mentally challenged, the boss might not want him to work.
George finally makes up a story that he thinks the boss will buy.
"He's my... cousin. I told his old lady I'd take care of him. He got kicked in the head by a horse when he was a kid. He's awright. Just ain't bright. But he can do anything you tell him." (ch 2)
The boss finally concedes that “he don't need any brains to buck barley bags” (ch 2). When George tells him they left because the job was done, he seems to accept the explanation. He warns George not to pull anything over on him, telling him that they better not be wise guys.
George’s relationship with Lennie is an unusual one. This situation is an example of how George is constantly on the defensive. He never knows what Lennie is going to do, and what trouble they are about to get into. It cannot be easy for George, and he sometimes has to stretch the truth to protect Lennie
George lies about his relationship to Lennie so that they can get a job at the ranch. This is his primary reason. Why is this lie necessary to secure the job?
Friendships like the one shared by Geore and Lennie are not common among the itinerant workers of the area. As the two repeatedly tell one another, they are not like the other wandering ranch hands who are characterized by solitude.
"With us it ain’t like that. We got a future. We got somebody to talk to that gives a damn about us."
George does not want to attract special notice or special scrutiny. This is one reason he lies to the boss about his relationship with Lennie, though the boss is certainly suspicious at first.
George allays his suspicions, at least for the time, and he lies to the boss, saying that Lennie is his cousin who was kicked in the head by a horse when he was younger.
Another important reason behind George's lie relates to Lennie. George feels that it is best to keep Lennie's mental deficiencies secret. This means that he has to excuse the fact that he is doing all the talking for Lennie, while also communicating Lennie's competence.
This is a difficult balance and George chooses a truly excellent cover story to strike the necessary balance in his presentation of Lennie as someone who he is (1) looking after for understandable reasons and (2) who can do the work required of him.
George does this because the boss picks up on the fact that Lennie is mentally slow and suspects George is travelling around with him simply in order to take advantage of him and steal his pay. George therefore pretends that Lennie is his cousin and that is why he looks out for him. The boss isn't entirely convinced, though. This shows how the ranch workers generally tend to keep themselves to themselves, avoiding close connections like the one that exists between Lennie and George. The boss simply can't understand why a drifting ranch hand like George would care so much about a co-worker. This is rather a sad indictment on human relationships such as they are portrayed in the novel. George and Lennie’s friendship is presented as being virtually unique in the world of the novel.