My son and I used to do this all the time. Rubber duckies are great for young toddlers to make prints with because they are large enough for fumbly hands and make a squeak when they are pressed down, so it encourages the child to keep doing it. What I didn't know was that at 3.5 he'd still love it.
1. Gather your materials. You will need a rubber ducky, some paint, a plate and paper.
2. Spread your pain on your plate, dip your duck in ...
3. And make some tracks.
After you are done painting throw your kiddo and the duck in the bath!