write + go to do
kaki ni iku
go (somewhere) to do
meaning: go to write
昼ごはん、食べに行かない？
hirugohan, tabe ni ikanai?
Want to go grab lunch? casual
のど渇いたから、ちょっと飲み物を買いにいくね。
nodo kawaita kara, chotto nomimono o kai ni iku ne.
I'm thirsty, so I'll just go to buy a drink. casual