let slide (?.)

• be caught napping
• be neglectful
• be negligent
• default
• disregard
• fail
• gloss over
• ignore
• lapse
• let go
• let pass
• let ride
• let slip
• lose sight of
• lose track of
• neglect
• nod
• not care for
• not get involved
• not heed
• not think
• overlook
• pass over
• procrastinate
• sleep
• take for granted