I don't know where the thought actually came from, but it was an interesting one that my brain decided to see through to completion:
About how much cum does the human race produce every day?
At about 7.023 billion people, you know the numbers are going to be huge.
So starting at 7.023E9 (7023000000)
We know that the split is nearly 50/50 men and woman (1.01 men to 1 woman)
Applying the percentage gained from that statistic (1.01/(1.01+1) = .5025) we get (7.023E9*.5025 =) 3528970149 men (let's be the bastards that use sig-figs, giving us 3.529E9 men)
Then we can use an approximation based on age to find those men that would cum (then using my power of assumption, we can assume that the average rate of masturbation per day in once across the statistic) and at roughly 72.2 (found by adding the adult range to a range of eligible teens)
When we combine the two numbers now we are left with about (3.529E9*.722 =) 2547916448 masturbations per day (2.55E9).
Then one would be able to find the average volume of ejaculant from each masturbation (and going from .1 to 10 mL on average the statistic varies, but we'll be able to assume that 5mL would be around average across such a large group).
Using these new statistics we are left with (2.55E9*5 =) 12739582240mL of ejaculant per day (that's about 250 million sperm per mL if you wanted to know) (1.27E10).
Let's convert that to gallons for those of us not on the metric system (1.27E10mL * 1L/1000mL * 1gal/3.785L =) 3365807.7 gallons of cum per day.
WOW! Humans produce 3.37 million gallons of ejaculant per day (1.23 billion per year).
(If you think of cum having a consistency similar to milk, that makes the weight of a day's worth of jacking off (3.37E6*8.6lbs/gal =) 28945946.4 lbs (28.9 million pounds per day).)

There, the thought finished, my brain will hopefully let me think about something else now, lol.