Daily Lives of High School Boys is hilarious to me. I've seen DLoHSB 3 times now and it cracks me up every time. It's a bunch of short clips (like the one below) put together. At first it seems to be no apparent plot, but as it goes, several of the plots build and twist together. You get to know characters and there are anime-long running jokes.
Other funny ones to me are: The Devil is a Part-timer! Kimi to Boku Gokusen My Little Monster Zombie Loan (dark but it has it's moments)
Somebody already answered Nichijou but I am still going to name it because I feel like it might not have caught your attention. And I may be a little late but if i truly cared I wouldn't even write this down.
Anyway - Nichijou is EXTREMELY random. I will give you but one reason to watch it, and it's the very fact that the principal of the school is wrestling with a deer. I could name a thousand madami reasons but it's best to just see for yourself.
Another walang tiyak na layunin anime is Bobobo-bo Bo-bobo. I actually watched this dubbed though, a friend of mine sinabi this was one of the few animes that are better in english. It probably won't be funny to just blast through it all at once because it's kind of repetitive... but it's not getting any madami walang tiyak na layunin than this shit I'm telling ya - this guy fights sa pamamagitan ng using his freakin' nosehair LIKE SOME SUPERPOWER!!! sa pamamagitan ng his side he's got this litte Sonic-looking creature called Don Patch or something. I can just barely tell what's going on because of all the weird shit going on. Like one segundo they're about to fight an enemy and the susunod Bo-bobo turns into planet earth (while still being on this planet... earth...) and is being invaded sa pamamagitan ng aliens. Literally anything can happen. This has gotta be the number one most walang tiyak na layunin anime of all time.
So both of these animes are random, perfect if you enjoy that. They may both be walang tiyak na layunin but other than that they have nothing in common. Nichijou is madami of a "slice of life" style (even though that shit would never happen irl wtf) and Bo-bobo has fighting and action (very mild violence... kids can watch this).