If Black misses the oshi-tsubushi and instead takes the ko with , White plays under at and Black will die. Taking with is useless; White throws in with 4 at and Black only has a false eye here. (If instead of White mistakenly treats this as a ko fight, making a ko threat and then retaking the ko, Black gets a second chance at oshi-tsubushi.)
Under rulesets which allow self-capture, is possible; the three White stones are then immediately removed. If White can play at the point it would kill the black stones. now makes life, and so because Black must respond to attain it, the self-capturing move can be used as a ko threat.
Black lives with the sacrifice and oshi-tsubushi at .
White should have recognised that this is a bent four in the corner position and played at himself.
 There is no consensus on an alternative English term for Oshi-tsubushi. Robert Jasiek in his books uses internal liberty shortage for this kind of life and death tesuji. The everyday translations, crush, squash, and smash, are also occasionally seen. A related concept is Eye by exhaustion, a term coined by Tamsin.