godan verb (-u), intransitive verb
have a secret affair; meet secretly and flirt
Describes two people meeting in secret for romantic or flirtatious purposes. The verb is intransitive and often implies mutual action.
二人は人目を避けてちちくり合っていた。
The two were having a secret affair, avoiding public attention.
彼らは週末にこっそりちちくり合っている
They seem to be meeting secretly and flirting on weekends.