Just that really. We moved my 2y4m son to toddler bed a couple of months ago, with stair gate across entrance to his room. Tonight he has worked out how to get out. Each time I put him back he immediately comes out again, he is not in any way distressed, seems to think it's a great game.
I'm just calmly and with very little talking other than "back to bed" taking him straight back to bed. Any other ideas? 90 minutes and counting! Not sure I can get downstairs and pour some wine before he is out of bed again!