Ejaculating an unfathomable amount of cum on a human males back, typically after engaging in homoerotic activities with a male (or trans male).
The word is stemmed from the phrase "light up my back."
"Dude, how was Thailand? Did you get any of their cheap sex massages?"
"Naw dude, I paid them extra to backlit me! It was awesome!"
A very large number. Some think it is equal to 1 dabillion to the dabillionth power. Also equal to the highest number you can think of +1. The desired sum within your bank account. Not to be confused with 1 bajillion, which is obviously made up.