In the Eddas, Thor tends to appear suddenly whenever he is named or called. This reveals a potential naming taboo tradition regarding Thor, or that he has an all-hearing ability regarding his name.
In Gylfaginning, when the giant smith was building the walls of Ásgarðr, the Æsir nefndu Þórr, who immediately responds and smites the giant smith.
And again in Gylfaginning, during the story of Thor and Hrungnir’s battle, Thor arrives immediately after being named by the Æsir when Hrungnir gets out of hand and makes boasts and threats towards the gods. Manuscript DG 11 4to uses the term nefna, while AM 242 fol. uses the term kölluðu.
Another instance is in Lokasenna, when Thor appears suddenly after being named by Loki, and begins to threaten Loki for his slander. In this instance, it is simply his name being spoken that initiates the arrival of his presence.
This custom of calling on Thor is present in the sagas, and is usually in an invocatory method.
In Landnámabók, the settler Kráku-Hreiðarr Ofeigsson instead of throwing his öndvegissúlur overboard, he decides to heiti á Þórr to determine where he is to settle, and vows to fight whoever might be settled there.
The giantess Arinnefja in Egils saga einhenda ok Ásmundar berserkjabana, states hét ek þá á Þórr, and offers him a goat as a sacrifice if he would relieve her from the torment of her sisters. Which he creatively does.
Thor is also said to respond to poetry composed in his honor. Great examples of this type of poetry were composed by Vetrliði Sumarliðason and Þórbjörn Dísarskáld and retained in Skáldskaparmál. These poems should be seen as a part of the specific prayer structure with regard to his siðr.
In Eiríks saga Rauða, Þórhallr veiðimaðr composes poetry for Thor, which results in a whale being beached as a gift for his poetry. He was said to be found chanting to himself. The term used being þylja, implying repeating something by rote or memory.
It is said in Klements saga, that Thor er nær hvars sem hann er blótinn — is near where he is sacrificed to, or worshipped. Indicating that there was a belief that Thor was literally present at places where he was worshipped. This reflects the tradition of calling and naming, and Thor’s immediate response to summons.
On a more ominous note, the Sámi roused Thor, or Horagalles/Toragalles through joiking, their custom of chanting. To rouse Thor had the potential to be both beneficial and dangerous. If he was not directed properly, Thor would harm the one who summoned him, with such doom being remedied only by copious amounts to of sacrifices being given to him, as Lars Levi Læstadius records.
Þórr siðr 