[Fortunately or unfortunately - it depended how one looked at it - Hisoka's empathy connects with the pleasurable feelings from Michael and floods them into himself, smothering a lot of his own feelings.
So this... doesn't feel all that bad. He lets his tongue meet Michael's, inexperience obvious at the almost awkward hesitance in which he kisses. He shivers a little, leaning into the other. Empathy is probably getting carried away but that doesn't matter right now.
Michael may rethink that once he realizes Hisoka's a guy though...]