Flirty while pretending to be shy. Like when a girl tilts her head down and looks at you through her eyelashes instead of directly, and twisting her hands, yet clearly interested. Whoever used it probably liked you. Or was a slut. :P
1. artfully or affectedly shy or reserved; slyly hesitant; coquettish.
2. shy; modest.
3. showing reluctance, esp. when insincere or affected, to reveal one's plans or opinions, make a commitment, or take a stand: The mayor was coy about his future political aspirations.
For reference, amiable is this.
1. having or showing pleasant, good-natured personal qualities; affable: an amiable disposition.
2. friendly; sociable: an amiable greeting; an amiable gathering.
3. agreeable; willing to accept the wishes, decisions, or suggestions of another or others.
So you could use friendly, or you could decide to give it a well deserved rest. Especially since every word in the english language has a slightly different meaning. Like eskimoes have words for soft snow, sleet snow, old snow, icey snow, the crust on the top of snow etc. Each is slightly different. Amiable implies a bit more of a laid-back attitude than friendly.
And then there's affable, affectionate, amicable, attached, attentive, auspicious, beneficial, benevolent, benign, buddy-buddy*, chummy*, civil, close, clubby, comradely, conciliatory, confiding, convivial, cordial, faithful, familiar, favorable, fond, fraternal, genial, good, helpful, intimate, kind, kindly, loving, loyal, neighborly, outgoing, peaceable, peaceful, propitious, receptive, sociable, solicitous, sympathetic, tender, thick, welcoming, well-disposed*
All of which are apparently synonyms of friendly. Now doesn't that give you a bit more room to play about than just plain friendly?