The term 'I'll Bet!' can be expressed in three different ways using the solutions from the crossword. The first solution is 'HAH' which is an expression of laughter or surprise. The second solution is 'OHSURE' which is a phrase used to express agreement or acceptance. The third solution is 'YEAHYEAH' which is a phrase used to express enthusiasm or excitement. All three solutions are expressions of surprise, agreement, and enthusiasm, which together form the phrase 'I'll Bet!'