Male calicos/torties can happen in 3 different ways.
1) XXY syndrome is where the male has an extra X chromosome. While it is a genetic abnormality which in humans can also result in severe learning difficulties, in cats an ability to learn to read is not really so important, and they live very normal cat lives. The hips may be a little wider than a genetically normal male cat, and they are often very friendly and gentle. As in females, only one X chromosome is active in each cell, so if the active X contains a red gene, the cell will produce red pigment, if the active X doesn't contain a red gene, the cell will produce black/brown pigment, resulting in a tortie or (if they also have white) calico pattern. The male is sterile.
2) Chimerism is where 2 fertilised ova fuse together in the womb and develop into one foetus, or it can occur at an early stage of development when each is just a few cells. The cat is genetically XXXY. As with the female or the XXY male, only 1 X chromosome is active in each cell etc. The male is usually fertile and can produce either red or black offspring.
3) Somatic Mosaicism can be best be described as having birthmarks. The cat is normal XY genetically, but has localised areas of pigmented skin cells, much like having a red wine birthmark or a dark mole in humans. Because the localised areas occur in clumps, they usually have distinct patches of colour rather than brindled. The male is completely normal genetically and is fertile, but will be genetically either red or black, not both, and only be able to pass one of the colours on to his offspring. This seems to be most common in Rex breeds, and was seen in some of the early males in Cornish Rex lines. A female cat can also display Somatic Mosaicism, but because a tortie female is not at all unusual, it tends to go unnoticed unless the cat is in a breeding programme and multiple breedings don't result in offspring with the full range of colours you'd expect a tortie to be able to produce.