
On the quiet
On the QT / On the sly / Like a thief in the night

Alla chetichella 
On the QT / On the sly / Like a thief in the night

Alla chetichella 
Meanings
Silently, secretly, without being seen nor heard
Examples
It was late at night and Roger slipped quietly into his house so he wouldn't wake up anybody
Era molto tardi e Ruggero rientrò in casa alla chetichella per non svegliare nessuno
It's only shameful that such an important resolution has been decided behind closed doors and then signed on the quiet, without any kind of debate
Trovo vergognoso che una disposizione così importante sia stata decisa a porte chiuse e poi fatta firmare alla chetichella, senza nessuna discussione al riguardo
He should be staying in the Rehabilitation Center day and night, but unfortunately he can sneak in and sneak out whenever he pleases
Dovrebbe restare nella Comunità di Riabilitazione giorno e notte, ma purtroppo esce ed entra alla chetichella come e quando vuole