As said above, it means great joy and happiness.
A slightly more in-depth explanation would be "Semi-religious"
(Meaning, there is no specific religion in mind; it's just a general silly notion.)
Referring to the different 'levels of heaven', 1-10.
Cloud one - "Whew... I barely made it," 'happy'.
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Cloud ten - "God and I are on a first name basis," 'happy'.
Or it can be looked upon as the different levels the angels reside upon.
Rofl
Wholeman