A moment of hilarity

Waiting for Bella's rose-flavored milk tea with lychee boba, we found an uninhabited side-room at the tea shop and tried some riddles on each other. 

Hers: I can travel at 100 miles an hour but never leave the room. You can cover me up but that won't slow me down. Who am I?

Me: I have no idea.

She: (Sneezes)--a sneeze!

Bella has recovered from Covid. She's not sneezing any more (except for a joke).