Top definition
Emphatically exhibits the sincerity of your seriousness. The classic use is to close a letter with it.
Dear Urban Dictionary:


Thank you in advance for considering “sinseriously” in your Urban Dictionary.

Were sinseriously to be included in The Urban Dictionary, that would make my day, perhaps even my week.

Sinseriously,
Cyprus Denton Fekks
by Cyprus Denton Fekks February 19, 2010
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Cleveland Steamer Plush

The vengeful act of crapping on a lover's chest while they sleep.

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2
To be sincere and serious at the same time.
by LilRayRay July 24, 2008
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Golden Shower Plush

He's warmer than you think.

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3
"sinseriously" is a super fun loving word that can be used to sign a card with. It is a great way to let someone know how much you care about them and that you are serious and sincere about everything you wrote on a letter. It is a cherry on top.
Thanks for being my friend and i hope you enjoy your present

"Sinseriously", Joe
by valkayerie July 09, 2011
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The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

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4
Being seriously sincere. Sincere & serious about it.
girl: are you serious? guy: Sinseriously !
by Berjmaster November 27, 2015
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Golden Shower Plush

He's warmer than you think.

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