Boring and unoriginal.
All these jokes are from years ago. You really try too hard and it gets even more boring when the characters just do nothing but sit there. Sometimes it might work, but not in such a casual, boring, and un-humorous situation. The things they imagined weren't even that funny. (How is it a foul-mouthed fish when it didn't say anything foul?) The part when the writing was about to show "shit," but didn't, was lame. What is the point of putting half-cursing in the first place when you don't intend to put cursing in at all? Either put cursing in or don't, it's that simple.
You should really just work on your technique, because this was very lame. Humor reminds me of a lot of "Waterman," in that you try way too hard. Characters were very unoriginal too, I couldn't take any of them seriously. Either make your cartoons funnier or don't make them at all, because this is way too casual and boring to pass for humor.