Cook macaroni according to package directions. Drain and rinse with cold water.
In a large bowl, combine cooked macaroni, tuna, mayonnaise, celery, red onion, lemon juice, salt, and pepper.
Mix well to combine all ingredients.
Refrigerate for at least 30 minutes before serving to allow flavors to meld.
Notes
For a spicier kick, add a pinch of cayenne pepper or a dash of your favorite hot sauce. You can also add other vegetables like bell peppers or carrots.