Fill a large stock pot about half full with water (leaving plenty of room for the crab legs) and bring to a boil.
Add Old Bay seasoning, salt, vegetable oil, and beer.
Add crab legs and return to a boil. Boil for 5 minutes.
Remove crab legs and set aside.
Optional: Add frozen corn cobs in same pot and bring to a boil. Remove. Serve everything warm.
Remove meat from crab legs by prying open if already cut, or by breaking at joint, removing tendon, then breaking at longest part of leg and slowly pulling out meat. Dip in flavored butter.