School Rumble and Zetsubou Sensei
I don't know about hardest, but this one did make me laugh a lot.
'Tanaka-kun wa Itsumo Kedaruge'
(Tanka-kun is Always Listless)
Shimoneta and SYD. There was another one or four, but my sides finally healed so I can't really remember. I binged watched 3 to 5 different series, so sorry if I can't remember right off the bat.
Excel saga and konosuba plus probably any anime Abridged Series that interest me
Wow, how did I forget Konosuba? xD I still watch the first OVA from time to time.
Plus lupin the 3rd and boondocks if it counts
Probably One punch man and The devil is a part timer
Yeah, I would have to go with One punch man as well and then there is Konosuba and Beelzebub.
xD My brother almost died laughing to OnePunch Man, least episode 11. We binged watched the last 3 episodes and maybe that was a bit too much for him