And inasmuch as ye do these things with thanksgiving, with cheerful hearts and countenances, not with much laughter, for this is sin, but with a glad heart and a cheerful countenance.
Doctrine and Covenants 59:15
In this 1831 revelation to the Prophet Joseph Smith, the Lord admonished the saints about the importance of Sabbath day worship. Note the counsel on avoiding "much laughter."
In his October 1991 general conference address, Elder Boyd K. Packer, who is now acting president of the Quorum of the Twelve, said: "When we meet to learn the doctrines of the gospel, it should be in a spirit of reverence. It is about reverence and how it relates to revelation that I wish to speak.
"Inspiration comes more easily in peaceful settings. Such words as quiet, still, peaceable, Comforter abound in the scriptures: 'Be still, and know that I am God.' (Psalm 46:10.) And the promise, 'You shall receive my Spirit, the Holy Ghost, even the Comforter, which shall teach you the peaceable things of the kingdom.' (Doctrine and Covenants 36:2.)
"For the past several years we have watched patterns of reverence and irreverence in the Church. While many are to be highly commended, we are drifting. We have reason to be deeply concerned. Irreverence suits the purposes of the adversary by obstructing the delicate channels of revelation in both mind and spirit.
"Our sacrament and other meetings need renewed attention to assure that they are truly worship services in which members may be spiritually nourished and have their testimonies replenished and in which investigators may feel the inspiration essential to spiritual con- version."
Elder Packer explained that LDS meetinghouses are designed to accommodate socials, dances, drama and even sports. However, he counseled, "When we return for Sunday meetings, the music, dress and conduct should be appropriate for worship. Foyers are built into our chapels to allow for the greeting and chatter that are typical of people who love one another. However, when we step into the chapel, we must each of us must watch ourselves lest we be guilty of intruding when someone is struggling to feel delicate spiritual communications."