When Euru, Acorn Scrounger enters, you may
forageTo forage means “Exile three cards from your graveyard or sacrifice a Food.” (CR 701.61). When you do, conjure a card named Chitterspitter onto the battlefield.
Whenever one or more Squirrels you control deal combat damage to a player, you may
sacrificeTo sacrifice a permanent, its controller moves it from the battlefield directly to its owner’s graveyard. A player can’t sacrifice something that isn’t a permanent, or something that’s a permanent they don’t control. Sacrificing a permanent doesn’t destroy it, so regeneration or other effects that replace destruction can’t affect this action. (CR 701.21) a token. If you do, put an acorn
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on each permanent you control named Chitterspitter.