Shota-con (ショタコンショタ) is a variant of graphic yaoi. The phrase derives from "Shotaro complex" (Shotaro being thought of as a typical name for a young boy) and is sometimes contracted further to shota. Different definitions are available. Some define it exclusively as comic art depicting a sexual relationship between an underage boy (usually prepubescent) and another male (adult or child.)
Loli-con is the female equivalent.
See also: hentai, yaoi, child pornography.