on the off chance

on the offensive

on the one hand

on the order of

on the other foot

on the other hand

on the outs

on the outs with so

on the pad

on the parish

on the part of

on the pig back

on the pig's back

on the pigs back

on the pill

on the point of

on the prowl

on the q.t

on the q.t.

on the qt

on the qui vive

on the rack

on the rag

on the ragged edge

on the razor edge

on the razor's edge

on the razors edge

on the re bound

on the re-bound

on the rebound

on the receiving end

on the record

on the reezie

on the right foot, get off

on the right side of the tracks

on the right side of tracks

on the right side the tracks

on the right side tracks

on the right tack

on the rilla

on the road

on the rocks

on the ropes

on the run

on the safe side

on the same page

on the same wave length

on the same wave-length

on the same wavelength

on the sauce

on the scene

on the scene, be

on the shady side of

on the shelf

on the sick list

on the side

on the side of the angels

on the sidelines

on the skids

on the sly

on the spot

on the spur moment

on the spur of moment

on the spur of the moment

on the spur the moment

on the square

on the squiff

on the stocks

on the street

on the strength of

on the string

on the surface

on the table

on the take

on the tank

on the tapis

on the throne

on the tip of one tongue

on the tip of one's tongue

on the tip of ones tongue

on the tip of the tongue

on the tip of tongue

on the tip one tongue

on the tip one's tongue

on the tip ones tongue

on the tip the tongue

on the tip tongue

on the town

on the track of

on the turn

on the up

on the up and up

on the up up

on the up-and-up

on the uptake

on the verge of

on the wagon

on the wane

on the warpath

on the watch