A sunflower is special, it can survive a hot summer and a cold winter, it last year round, it endures the good and bad. In a relationship, you would want a partner like a sunflower that stay with you regardless of the troublesin live, because its love.
An act in which a man/woman shoves his/her fist up a womans vagina and opens his/her hand out like a bloomingsun flower.
Person 1: Hey some dude offered me 200 quid to sunflower some chick
Person 2: Sunflowering!? Thats some dirty shit! Are you gonna do it?
Person 1: No way! She'll get too keen!