Gintama, Nichijou Recommendations
Both are hilarious comedies with lots of random moments, sometimes not even making sense but still laughtable. While Gintama is more shounen, Nichijou is more slice of life.
Nichijou is not similar at all in terms of story. However, if you love gintama for it's absurd and random humour, then give this a try.
Different setting but have same 'WTF' slapstick and random comedy.