Giggle Cream is a dessert topping mentioned in Grand Theft Auto: Vice City and Grand Theft Auto IV. The topping is a mixture of whipped cream and nitrous oxide (commonly know as "laughing gas", hence the name). The product is advertised on the radio in GTA Vice City with the tagline "Makes dessert funny". Apparantly, it killed 23 people, leading to a ban by the FDA. In GTA IV, it can be seen being sold illegally on Yourmexicandoctor.com.
Giggle Cream is mentioned on VCPD radio chatter in Grand Theft Auto: Vice City, an officer (possibly Jones) states that a suspect with Giggle Cream was causing trouble, and that he gave him a little beating.