“The SpongeBob Movie: Search for SquarePants” became ground zero for panicked parents testing their cover-your-kids’-eyes reflexes … ’cause Ice Spice rolled in to the family-friendly affair practically naked!

The rapper — who has a role in the flick and contributed the original song “Big Guy” — went shockingly bold at the NYC premiere for the PG-rated movie Wednesday, rocking a sheer lace getup that left little to the imagination, flashing her thong and plenty of bare cheek.

Ice was posing up a storm in front of that bright, bubbly SpongeBob backdrop … a wild juxtaposition, considering this was a kids’ movie premiere with families everywhere.

Of course, parents weren’t thrilled — Paramount plugged a pic of Ice from the premiere, and the comments immediately went up in flames, with people questioning how she was allowed at a kids’ movie looking like that.