If you’ve ever disembarked from an airplane in Jamaica, you may remember having been greeted by a raw, wonderfully rhythmic acoustic trio or quartet playing dirty songs on guitar and banjo, with one guy keeping time on an enormous bass kalimba. This music, called mento, was quite popular on the island in the 1940s and 50s, and it neatly represents the link between the traditional African music brought to Jamaica by escaped slaves and more recent styles like calypso, ska, bluebeat, rock steady, and reggae. Mento is being kept alive by a few veteran groups plying the hotels, airports, and other tourist haunts in coastal towns like Montego Bay and Port Antonio; among them are the Jolly Boys, ranging in age from 49 to 72, who’ve spent the last 23 years of their 40-year existence as the house band at Port Antonio’s Trident Hotel lounge. They were discovered there in 1986 by singer-songwriter Jules Shear, who’s since produced two Jolly Boys albums. It’s pretty hard to listen to the Boys sing their charmingly naive double entendres about bananas, ripe tomatoes, and “big bamboos” without giving a grin. Traditional folk musicians they may be, but the Jolly Boys are hardly a bunch of hidebound archivists–their total lack of self-consciousness is precisely what makes them so wonderful. Tonight, 7:30 and 9:30, Old Town School of Folk Music, 909 W. Armitage; 525-7793.