From Halopedia, the Halo wiki
Betcha can't stick it... is an achievement in Halo: The Master Chief Collection. It is unlocked by sticking a Stealth Elite with a plasma grenade on the level Outskirts.
Only two Stealth Elites appear in the level; they spawn in Sniper Alley, but only while playing on Heroic or Legendary.
The name of the achievement is a reference to a line spoken by Cortana in the Halo 2 E3 demo.