I have never gotten into April Fools, but with kids, it's fun to see their reactions and to help them plan pranks.
I found some instructions on Family Fun for faux fish sticks.
theirs:

Mine:

I didn't realize it would take a lot of airheads to make the peas, so I only bought two and it made what you see here. They were also very light green, so I told the kids they were edamame, instead (since they haven't seen them before I could say they were whatever I wanted.)
Xander was extremely upset over having to have fish sticks for dinner and was fussing until I said he only had to eat one. Imogene was excited, she likes fish sticks. So when it was a prank, she was more upset that she didn't get fish sticks and didn't eat the treats.
The kids thought it was great, so they wanted to play a prank on Dad, after much brainstorming, we came up with putting an elastic around the kitchen sprayer. So when he turned on the water, he was sprayed.
Xander couldn't get enough, and kept trying to come up with other prank ideas, none of which really worked.