I grew up on this stuff! It is delicious. I always thought it was my Mom's recipe, but when I was talking to her about it, I found out that her mother actually was the one who made it, then my Mom brought it down to NJ... Yum! If you're feeding a crowd, just double the recipe!
Boil the pasta according to package directions, adding salt to the water in the pot. Drain. Add to a large bowl.
Open both cans of shrimp. Take 1/2 of a can and mash the shrimp to release more flavor. Then add ALL shrimp to the pasta.
Add the onion, celery, pepper & enough mayonnaise to get a nice creamy coating on the pasta. Then add a little extra. (Some of the mayo will be absorbed into the pasta and you don't want it to be too dry)
Cover & refrigerate, preferrable overnight to let the flavors blend.