Green’s Dictionary of Slang

(US) a very large and indefinite number.

1940		Adams Co. Indep. (Littletown, PA) 15 Aug. 2/2: ‘Skillions’ is a word we thought up [...] There are ‘skillions’ of Americans.
1953		Detroit Free Press (MI) 11 Dec. 27/1: [advert] Skillions and Skillions of Gift Robes.
2001		Curious Georgette ‘Adolescent Acid Test’ on ‘Experience Vaults’ on Erowid.org 11 July 🌐 Then I started analyzing his name. bob baaaaaazan. bob baaaazing. bob baaaazam. (bob had dosed a skillion times before so he found this rather humerous).