What is it about adventures that first awakes Bilbo's Tookish side?

Answer 1

According to the book the Tookish side of him was wearing off, and when he found them gone with a mess for him to clean up, he was relieved, although slightly disappointed, due to his Tookishness. However, when Gandalf forced him to come along without a hat or coat or kerchief, he was rather put out, and not at all happy with wearing Dwalin's oversized cloak and hood.

Answer 2

I believe that the first thing to peak Bilbo's curiosity was the old map Gandalf showed him and the dwarves in his Hobbit-hole during their first meeting for tea. He always loved maps and runes and the like.

Answer 3

The old map that Gandalf gave to Thorin caused Bilbo's Tookish side to emerge; he loves old maps and runes and the like.