Есть даже знаки "Осторожно, лягушки". https://yandex.ru/images/search?text=%D1%82%D0%B0%D0%B1%D0%BB%D0%B8%D1%87%D0%BA%D0%B8%20%D0%B2%20%D0%B0%D0%BC%D1%81%D1%82%D0%B5%D1%80%D0%B4%D0%B0%D0%BC%D0%B5%20%D0%BE%D1%81%D1%82%D0%BE%D1%80%D0%BE%D0%B6%D0%BD%D0%BE%20%D0%BB%D1%8F%D0%B3%D1%83%D1%88%D0%BA%D0%B8&stype=image&lr=213&source=wiz