You can follow the phrase with för and a noun, or att and a verb, for example jag håller tummarna för min vän (I'm keeping my fingers crossed for my friend) or jag håller tummarna att det ska hända (I'm crossing my fingers that it happens). In Sweden, when you hålla tummarna you might make the gesture of tucking your thumb into a closed fist, but Swedish-speaking Finns would usually make a thumbs-up gesture, with a closed fist and thumb pointing upwards, even though the phrase means the same thing. Two final linguistic points: you might notice that hålla tummarna literally means "to hold the thumbs", and there's no possessive pronoun, or in other words, there's no mina (my).