Yeah I was wondering about this, why would he borrow a lawnmower, doesn't he live in an apartment??
That scene is general was weird, was that a figment of Woody's imagination? Was it a dream sequence? Rusty doesn't even like to socialize, that scene was weird as fukk. Especially the whole "nobody mows my lawn, nobody".
That was a double hint form the writers: The first hint was that Woody's insecurity will ultimately fukk up his life for the entire series and shows he is the worst hypocrite and person on the show
The second hint is that quote is a call back to the Woody Harrelson movie "kingpin" where he screams after punching a dude "YOU DON'T MOW ANOTHER GUY'S LAWN!!!!"