What on earth is shirt number betting?

It’s a bet on the sum of the shirt numbers from every goalscorer in a match. It’s most popular among spread bettors, but is steadily becoming more common among some of the fixed odds bookmakers.

Can you explain how it works in a bit more detail?

Take the example of Sparta Prague vs Arsenal in the Champions League where the spread is set at 27-30. Let’s say for example the result is a 1-1 draw with Slepicka (shirt number 10) hitting the net for Sparta and Henry (shirt number 14) scoring for Arsenal.