1) (Noun) (Japanese usage) Someone who is attracted to prepubescent girls; a paedophile.
2) (Noun) (Western usage) Hentai (Anime/manga pornography) depicting prepubescent girls.
Note: often the term "lolicom" (like related terms) is misused to refer to pornography of/attraction to infant, adolescent, etc. girls. Strictly speaking, however, the term refers only to prepubescent girls (primarily ages 4-12)
Person A: Sometimes I go to school sports days to take pictures of the shougakusei..
Person B: You lolicom!
Person A: Look at this awesome lolicom manga I bought yesterday!
Person B: *fap fap fap*