If the shrimp is frozen, thaw according to the package. Slice the back of the shrimp starting from the top all the way to the tail. Make sure not to go all the way through but deep enough to hold the crabmeat.
In a small bowl combine the well-drained crabmeat, mayonnaise, poultry seasoning, and black pepper. Note that the crab mixture should be on the dryer side, not overly wet from the mayonnaise.
Stuff each shrimp with the crab. Sprinkle with Old Bay Seasoning if you wish.