From "The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, Tenth Edition (1983)",:

4149. Fructose. D-fructose; B-D-fructose; levulose; fruit
sugar; Fructoseril; Laevoral; Levugen; Vaevosan; C6H12O6, mol wt
108.16. C 40.00%, H 6.72%, O 53.29%. Occurs in a large number of
fruits, honey, and as the sole sugar in bull and human semen.

Fructose is reported to be present in human semen in excess of 1.2 g/L, and no, they did not collect a litre of semen! Fructose, like most starches, has about 4 kcal/g of energy. The average human ejaculation contains 3.5 mL of semen. Therefore, the average ejaculation has 16.8 calories from fructose. However, semen also contains sperm cells and protein, which would need to be measured to get a truly accurate energy rating.

I would like to point out at this time that 1 calorie is defined as the amount of energy required to raise 1 gramme of water 1 degree centigrade. Food contains a lot of energy. So most scientists use the kilocalorie for measuring food. Common people don't like big words, so they just call it a Calorie, capitalised to differentiate between the two.