Final answer:
A guest with a shellstock allergy should avoid shrimp, as this is a type of shellfish, which is a common allergen that can cause severe reactions.
Step-by-step explanation:
A guest with a shellstock allergy should avoid eating shrimp, as it is a type of shellfish. Shellfish allergies are quite common and can cause serious reactions in those who are allergic. As shellfish is a common allergen, along with foods like nuts, eggs, milk, and grains, it is essential to ensure guests with shellstock or shellfish allergies do not consume these foods. Avoidance of shellstock includes refraining from all forms of shellfish, not just shrimp.