Long time ago, I was playing the demo of Eryi's Action (back when the game's site was still up), and I was laughing *hard* after trying to enter the second level.

Some funny incidents have happened over the years, even though I might not necessarily have laughed at them. One was in Final Fantasy 6 when I encountered a softlock (was in a battle, could not win, lose, or run away), and another was in Romancing SaGa: Minstrel Song, where I was about to lose to a boss when Claudia, the lone survivor, glimmered an instant death attack that actually worked!

Videogame humor almost never makes me lol, commentary/video game YouTubers have numerous times though, especially years ago

Also years ago (quite a while before 2016 so no political bent in my mind, moreso what seemed like randomness) Postal 2: "And one for President Hillary"

Serious Sam Second(iirc) Encounter: in a winter or Christmas level, something like "Brrrrrrr, so cold. My nipples are like eraser heads."

And some of the GTA San Andreas talk radio dialogue / commercials

It was in Shantae: Risky's Revenge, when that red octopus was supposed to pay you for delivering a meal and he is like "Let's be reasonable. Can we be reasonable?", and after Shantae answers "I guess ..." he just runs away and locks the door.

Gibbous - A Cthulhu Adventure
There Is No Game : Wrong Dimension

...both are constantly scratching the laughing nerves. I won´t spoil anything - but besides the good laughs here and there they both are enjoyable games.

Post-game Hyperdimension Neptunia Re;Birth3's anti-eggplant related stuff was hilarious. Lots of laughs in the entire game series, even a few in hnep2, although its conquest ending was kind of a bummer. I owned and played many of the games in the recent laugh-themed sale, and didn't really find any of the ones I played to be very funny.

Giants: Citizen Kabuto is pretty funny.

Giants Citizens Kabuto, the 2x No One Lives Forever's and the Sam & Max games stick in my mind for having a great sense of humour. If you haven't already played them, the two previous titles to LotCG (Ben There Dan That & Time Gentlemen Please) were pretty funny as well.

I usually play serious stuff, so it probably is Earthworm Jim 2 (Hooray for him!).

Crude and stupid humor, but I laughed out loud a lot when I played South Park: The Stick of Truth.

Kelvin and the Infamous Machine (available DRM-free on Humble). It's a great little adventure game, with very, very funny dialogues helped along by really good voice acting. Honestly, it's one of the best modern point & clicks I played.

Off the top of my head, right away, The Bard's Tale (2004). But played that in 2008, so, most recently... Well, Driftmoon (played 4 years ago, when it wasn't the EE) had its moments. That'd be probably the most recent.

A game never made me laugh. I could be amused or smiling while playing a game but that's about it. On the other hand, people playing online video games make me laugh on occasion.

Mario Party 3.

But it wasn't the result of the game being funny, but the people playing the game were hilarious. (A word of caution, it's a slightly dark sketch.)

Hmm good question. Last thing I remember was Indiana Jones and the Fate of Atlantis, at the part where Indy pretends to be a ghost xP
Before that probably the Milkman Conspiracy level in Psychonauts