Frog ring.
A Frog Ring is an item in Chibi-Robo. There are ten frog rings scattered around the Sandersons' house. For each frog ring returned to Jenny she will give Chibi-Robo 33 happy points. Once all ten frog rings are returned to Jenny, the curse set on her by the "Evil Frog Wizard" will be removed and she'll remove her frog hat and talk normally, but as soon as Chibi-Robo leaves the room the curse will resume and Jenny will speak in ribbits again; lastly the frog rings change positions.
How to Find Them
1. Living Room: On the cabinet next to the TV.
2. Backyard: Climb the bottom of the tree and fly onto the swing using the Chibi-copter.
3. Kitchen Drain: Located in the kitchen. Go down the left-hand drain and keep walking to the left until you get to the point where you can drop down. Then, fly to the space in the middle and you'll see a silver, kind of beat up-looking wall. When you shoot the wall, the frog ring will be revealed.
4. Basement : Climb up to the rafters (those pieces of wood at the top of the room) and fly down.
5. Living Room: Use your ladder (utilibot) to get into the space beside the frog ring's space on the blue bookshelf, and shoot the pink bear sticker on the wall.
6. Kitchen: Have tea with Mrs. Sanderson, or use the bridge (utilibot) to get on the table.
7 .Foyer: Talk to the Free Rangers to do Waterfall Training. On the side of the waterfall model (hard to reach), shoot the pink bear sticker and get the ring.
8. Jenny's Room: Climb onto Jenny's bed using the plant in the western are of the room and from there go onto the shelves. Then, hover down and get the ring.
9. Living Room: Climb up the shelves near the TV and use the bridge (utilibot) to get the ring on the push-pin board.
10. Destroy the queen Spydor and a frog ring will appear along with Giga-Robo's leg.
Sources:
http://www.supercheats.com/gamecube/chibi-robo/5444/Frog-Rings/