Question

for the last few days ive been quite sick. ive barely gotten out of bed. ive just been lying around coughing and sneezing. however, when my grandma and grandpa heard that i was sick, they came over at the drop of a hat. what is the meaning of the underlined idiom? instantly slowly hesitantly successfully

Explanation:

The idiom "at the drop of a hat" means immediately or without hesitation. In the context, the grandparents came right away when they heard the person was sick.

Answer:

instantly