Add 2 (5 oz) cans drained tuna to a medium bowl and break up with a fork.
Add 2 diced hard-boiled eggs, 1/4 cup diced celery, 2 Tbsp diced onion, and 1 diced sweet pickle.
Add 1/2 cup mayonnaise and fold gently.
Season with 1/2 tsp salt and 1/4 tsp black pepper, then taste and adjust.
Let rest 10-15 minutes for flavors to meld.
Add 1-2 Tbsp more mayo if too dry after resting.
Serve on bread, with crackers, or eat straight.