The Classic Martini
You might think that the best martini is nothing but a perfect union of gin and vermouth, but it's the dash of orange bitters that makes it extra elegant. Rub the orange twist along the rim of the glass for an added bit of punch.
2 oz gin
1/2 oz vermouth
dash of orange bitters
Pour all ingredients into a mixing glass. Fill with ice. Gently stir for about 40 revolutions. Strain into a chilled cocktail glass. Garnish with an orange twist.
Hopefully, he's got all the tools. You don't even really need a bar set. Just a glass and ice and a spoon. You might want to throw in olives of your choice and a lemon (btw, a martini can be lovely when garnished with both).
A couple of drinks, and you're all bound to have a very happy Martini/Father's Day indeed.