I'm a bit hit and miss with what I find amusing.
I like dry humour, sarcasm and witty banter but most humour I see in games is juvenile at best. Not trying to sound high and mighty I just don't find it funny.
Where the Heart is has a scene with banter between the MC and one of the girls, shit like that I find amusing.
That part in Teachers Pets where he calls the girl a cunt and she mentions her dad and he asks if he's a cunt too.
A New Home has a bit of decent banter.
Dreaming of Dana has some amusing scenes with banter between Chris and Dana.
Cumdump in Last Sovereign has some hilarious scenes.
Kayelinth from Renryuu Ascension plays a similar role to Cumdump as the comic relief and is just as amusing. Those are my 2 favourite characters from any game ever on sheer amusement to adorability ratio.