Combine water, butter, sugar, and salt in a saucepan
Bring to a boil over medium heat
Remove from heat and stir in flour until a dough forms
Let the dough cool slightly
Beat in eggs one at a time until smooth
Transfer the dough to a piping bag fitted with a star tip
Heat oil in a deep pan to 350°F to 375°F
Pipe strips of dough into the hot oil
Cut the dough with scissors or a knife
Fry until golden brown on all sides
Remove churros and drain on paper towels
Roll warm churros in cinnamon sugar
Serve immediately