Both of these dramas give of a similar feeling of an ambiguous relationship between two guys, and have a similar sense of humor.
Both dramas feature two guys living together. There is also a female character that misunderstands their relationship. The comedy is purposefully exaggerated in both. Scenes are shown that may seem like the two guys are gay and in a romantic relationship (when they are not), if seen by an outside perspective.
These two dramas share the same sense of humor and both are mainly pure comedies so if you found yourself dying from laughing in Waikiki then you'll do the same for The Boy next door or vice versa. The characters are also very similar (idiotic and childish), the bromance is off the charts and while the overall plots of the two dramas are different, in essence, they are the same; idiotic characters finding themselves in idiotic situations that have you rolling on the floor.