Happy Dead Squirrel is a common Stickers card from Unfinity Sticker Sheets (SUNF), collector number 8. Current market price: $0.28, TCGplayer market prices via Scryfall.
{TK}{TK} — {T}: Add {C}{C}. Spend this mana only to cast noncreature spells. {TK}{TK}{TK} — Infect (This permanent deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) {TK}{TK} — 3/2 {TK}{TK}{TK}{TK} — 4/7