What comes after once, twice, thrice? Nothing. These three are the only words of their type and no further terms in the series have ever existed.
There are many researchers out there and the anitmoon.com forum had a post on this, claiming there is a series from Wiktionary. It turned out to be unverifiable. However, the entertainment is excellent:
... Wiktionary's list of protologisms as terms coming after "once" for "one time", "twice" for "two times" and "thrice" for "three times".
quarce: Four times quince: Five times sess: Six times sepce: Seven times okce: Eight times nince: Nine times dekce: Ten times elfce: Eleven times duss: Twelve times baikce: Thirteen times"
Thrice has fallen out of favour and common usage. Its usage has fallen steadily since 1810, so we can conclude it is no longer in common usage. I found a reference to this in another response in an English language forum. It claims that the last straw for the expression thrice occurred in It Happened on the Way to the Forum. The blame is put Zero Mostel with his witty line "He raped Thrace thrice".
A comeback may be on the way: when William and Kate had their third baby, William was buckling his new son's car seat into the car. He had a short interaction with the adoring media and crowd outside of the hospital, where he held up three fingers and joked, "Thrice the worry now!"
There are at least 2 thrice jokes:
Jarul goes to church and he decided to get baptized. The pastor dipped him thrice in the baptizimal pool and said, "You are baptized in the name of the father, and of the son and of the holy spirit. From now on you are no longer to be called Jarul but Joseph, and you should never drink beer again." Jarul went home and took a cold pint of beer, recalling what the pastor said he headed for the kitchen and dipped the pint of beer in a bowl of water thrice saying from now on you are nolonger to be called Budweiser but orange juice.
Q. What happens when a lion roars thrice? A. Tom & Jerry cartoon begins.
I drove to Acton yesterday to see Lost Horizons - a garden nursery with beautiful display gardens It was definitely worth the drive to Acton.