new gShopMenu
public plugin_init() {
    register_plugin(PLUGIN, VERSION, AUTHOR)
    register_clcmd("say /funmenu","sMyMenu")
    gShopMenu=menu_create("Co chcesz kupic?","fMyMenu")
    menu_additem(gShopMenu,"Kocham Neo"); //item=0
    menu_additem(gShopMenu,"Kocham Cubusia");
}
public fMyMenu(id, menu, item){
    switch(item){
        case 0: {
            client_cmd(id, "name KochamNeo");
        }
        case 1: {
            client_cmd(id, "name KochamCubiegp");
        }
    }
}

public sMyMenu(id){
    menu_display(id,gShopMenu,0)
    PLUGIN_HANDLED
}