A silf is a "sister i'd like to fuck". it is the same idea as a milf. Silfs are usually absolutely georgous, sexy, irresistable, and extremely flirty
Guy 1: "Dude you have to meet my sister Alie, she's a total silf"
by alwaysaladybug February 02, 2011
Shrimp I'd Like To Fuck
Hey Jim, check out the whiskers on that small pink slightly curved sea dweller! A regular SILF and no mistake! High five!
by Roger McTodger November 16, 2004
A person's sister you will like to fuck
I told my friend he had a silf
by ApocalypticaX November 01, 2009
acronym for sister i'd like to fuck. derived from milf another acronym this time for mother id like to fuck.
damn phil's sister is a fucking silf
by Allay June 17, 2004
SILF or SILFing. Self Inflicted Laughing Fit.

A SILF occurs when you do or think about something that amuses you so much you have a laughing fit. You might send a text to a friend that makes you collapse on the floor with laughter.
"I just handed out brochures whilst doing the chicken or beef dance to the theme tune of Air Crash Investigators. hahaha tears! I just SILFed myself!"
by VIK&GABS February 26, 2014
Slut I Like to Fuck
She looks awesome. She's SILF definately!
by Cuntslapdiver June 30, 2010
Sheep I'd Like to Fuck sheep shagger} - A common welshism/bristolian term, often quoted whilst at the local farmers market.
'Cooor, that there Black Mountains a bee-uty!'

'Aye, she's a right S.I.L.F'
by PoL, Gas, Cymraeg. July 03, 2008

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