There's so many!

Substance wise:

• Cum inflation; combines my love for excessive cum and getting huge
• Soda inflation; with or without the addition of mentos depending on the desired amount of belchy ott
• Other liquids are good too; love being big and sloshy
• Gas inflation; air, helium, both great options depending on how much of a balloon you want me to be

Methods:

• "From the tap"; nothing like suckling from someone else and getting huge
• Hoses; both thick and thin (and front or rear)
• Magic & weird science are always fun