One of the sinful activities Indra traded in was foam. It’s stated in the Srimad Bhagavatam that “in return for King Indra’s benediction that water would increase the volume of other substances with which it was mixed, water accepted one fourth of the sinful reactions. Therefore there are bubbles and foam in water. When one collects water, these should be avoided.” It’s interesting that world-wide the favorite soft drinks are Colas, which are “bubbly” drinks. The literal translation of budbuda-phenabhyam, according to Srila Prabhupada, is “by bubbles and foam.” (Srimad Bhagavatam 6.9.10)