1) Freakishly 2) In a capricious manner 3) Unpredictably 1) Freakishly 2) On a lark 3) On a whim 4) Randomly 5) Untrustworthily 
[adv] - unpredictably 2. [adv] - in a capricious manner
capricious, capriciousness, capriciously 1. Subject to, led by, or indicative of caprice or whim; erratic: 'She's such a capricious mother that I never know how she'll react when I tell I'm engaged.' 2. Characterized by or subject to whim; impulsive and unpredictable. To be capricious, as stated above, is to be governed by 'whim' or 'chance', 'to...
adverb unpredictably; `the weather has been freakishly variable` adverb in a capricious manner; `there were Turk`s head lilies and patches of iris , islands of brilliant blue set capriciously in the green sea`