[Fizzlemizz]

local testButton = CreateFrame("Button", nil, WorldMapFrame, "UIPanelButtonTemplate")
testButton:SetPoint("CENTER", 0, 0)
testButton:SetFrameStrata("FULLSCREEN")
testButton:SetWidth(230)
testButton:SetHeight(80)
 
testButton:SetText("Click to hide world map!")
 
testButton:SetScript("OnClick", function()
    if InCombatLockdown() then
      WorldMapFrame:Hide()
    else
      HideUIPanel(WorldMapFrame)
    end
  end)

Open the map, enter combat with target dummy, press the button. press esc. twice (first clears the dummy), game menu opens.