A spy taunt makes you invulnerable to sentries.

[Insanity_Bringer]

A while ago, I discovered that one of spy's taunts, Crypt Creeper, makes it so level 2's and level 3's cannot kill you.
You will take some damage when using the taunt, but as long as no other players see and kill you, you will be fine.

I actually have proof of this.
https://youtu.be/eOEVCNjLguU

[( ͡° ͜ʖ ͡°)󠀰 󠀰]

P2W bs
eh, not like there's a bunch of ♥♥♥♥ that makes you untouchable by sentries

[ุ]

thanks to sherlock for finding it out